In type 1 diabetes, the pancreas does not produce insulin. Insulin is a hormone that is involved in regulating blood sugar (glucose) by controlling how much glucose you make between meals and how you store glucose that you absorb after a meal.
People with type 1 diabetes usually need to take insulin multiple times a day, or continuously from a pump, and must carefully monitor their blood glucose levels to avoid serious complications.
Type 1 diabetes can occur at any age. But it is most commonly diagnosed in childhood or adolescence.
Symptoms of both type 1 and type 2 diabetes include:
In general, the symptoms of type 1 diabetes come on more abruptly and are more severe than those of type 2 diabetes.
Hypoglycemia (low blood sugar) occurs when blood sugar (glucose) levels fall below normal. All patients with diabetes should be aware of these symptoms of hypoglycemia:
It is important to quickly treat hypoglycemia and raise blood sugar levels by eating sugar, sucking on hard candy, drinking fruit juice, or injecting the hormone glucagon. Patients who are at risk for hypoglycemia should carry some sugar product, or an emergency glucagon injection kit, in case hypoglycemia occurs. Patients should also wear a medical alert ID bracelet or necklace that states they have diabetes and take insulin.
Technology is moving forward in combining a device that adjusts the dose of insulin (and often a doses of a second hormone called glucagon) in response to continuous glucose monitoring. Due to both expense as well as need to further refine the technology, this type of the device is mostly still being used in research studies.
The 2 major forms of diabetes are type 1 (previously called insulin-dependent diabetes mellitus (IDDM), or juvenile-onset diabetes) and type 2 (previously called non-insulin-dependent diabetes mellitus (NIDDM), or adult-onset diabetes).
In type 1 diabetes, the body does not make any insulin or produces only a small amount of insulin.
Both type 1 and type 2 diabetes share one central feature: elevated blood sugar (glucose) levels due to not having enough of a signal from insulin, a hormone produced by the pancreas. In type 1 diabetes the reason the insulin signal is insufficient is because the amount of insulin in the blood is too low. Insulin is a key regulator of the body's metabolism.
The pancreas is located below and behind the stomach. In addition to secreting digestive enzymes, the pancreas secretes the hormones insulin and glucagon into the bloodstream. The release of insulin into the blood lowers the level of blood glucose (simple sugars from food) by enhancing glucose to enter the body cells, where it is metabolized. If blood glucose levels get too low, the pancreas secretes glucagon to stimulate the release of glucose from the liver.
In type 1 diabetes, the pancreas does not produce insulin. Onset is usually in childhood or adolescence. But it can occur at any age. Type 1 diabetes is considered an autoimmune disorder that involves:
Type 2 diabetes is the most common form of diabetes, accounting for 90% to 95% of cases. In type 2 diabetes, the body does not make enough insulin or does not respond properly to insulin, a condition known as insulin resistance. Over time, the pancreas may become unable to produce insulin in adequate amounts.
Gestational diabetes is a form of type 2 diabetes, usually temporary, that appears during pregnancy. It usually develops during the third trimester of pregnancy. After delivery, blood sugar (glucose) levels generally return to normal, although some women go on to develop type 2 diabetes.
Women who have type 1 or type 2 diabetes before their pregnancies do not have gestational diabetes.
Type 1 diabetes is considered a progressive autoimmune disease, in which the beta cells that produce insulin are slowly destroyed by the body's own immune system. It is unknown what first starts this process. Evidence suggests that both a genetic predisposition and environmental factors, such as a viral infection, are involved.
Islets of Langerhans contain beta cells and are located within the pancreas. Beta cells produce insulin which is needed to metabolize glucose within the body.
Researchers have identified at least 18 genetic locations, labeled IDDM1 - IDDM18, which are related to type 1 diabetes. The IDDM1 region contains the HLA genes that encode proteins called major histocompatibility complex. The genes in this region affect the immune response. Other chromosomes and genes that affect the risk of developing diabetes continue to be identified.
Most people who develop type 1 diabetes do not have a family history of the disease. The odds of inheriting the disease are only 10% if a first-degree relative has diabetes. Even in identical twins, one twin has only a 33% chance of having type 1 diabetes if the other twin has it. Children are more likely to inherit the disease from a father with type 1 diabetes than from a mother with the disorder.
Genetic factors cannot fully explain the development of diabetes. For the past several decades, the number of new cases of type 1 diabetes has been increasing each year worldwide.
Some research suggests that viral infections may trigger the disease in genetically susceptible individuals.
Among the viruses under scrutiny are enteric viruses, which attack the intestinal tract. Coxsackie viruses are a family of enteric viruses of particular interest. Epidemics of Coxsackie virus, as well as mumps and congenital rubella, have been associated with type 1 diabetes.
Type 1 diabetes is much less common than type 2 diabetes, consisting of only 5% to 10% of all cases of diabetes. Nevertheless, like type 2 diabetes, new cases of type 1 diabetes have been rising over the past few decades. While type 2 diabetes has been increasing among African-American and Hispanic adolescents, the highest rates of type 1 diabetes are found among Caucasian youth.
Type 1 diabetes can occur at any age but usually appears between infancy and the late 30s, most typically in childhood or adolescence. Males and females are equally at risk. Studies report the following may be risk factors for developing type 1 diabetes:
The process that destroys the insulin-producing beta cells can be long and invisible. However, at the point when insulin production becomes too low, type 1 diabetes usually appears suddenly and progresses quickly. Warning signs of type 1 diabetes include:
Children with type 1 diabetes may also be restless, apathetic, and have trouble functioning at school. In severe cases, diabetic coma may be the first sign of type 1 diabetes.
Diabetes increases the risk for many serious health complications. The good news is that during the past several decades, the rate of serious complications among people with diabetes has been decreasing, and more patients are living longer and healthier lives.
There are 2 important approaches to preventing complications from type 1 diabetes.
Diabetic ketoacidosis (DKA) is a life-threatening complication caused by a complete (or almost complete) lack of insulin. In DKA, the body produces abnormally high levels of blood acids called ketones. Ketones are byproducts of fat breakdown that build up in the blood and appear in the urine. They are produced when the body starts burning much larger amounts of fat than the body needs for energy. The buildup of ketones in the body is called ketoacidosis. Extreme stages of diabetic ketoacidosis can lead to coma and death.
For some people, DKA may be the first sign that someone has type 1 diabetes. In type 1 diabetes, it usually occurs when a patient is not taking insulin as prescribed, runs out of insulin, or cannot afford to buy medication. Sometimes patients intentionally reduce insulin doses in order to lose weight. DKA can also be triggered by a severe illness or infection that weakens the immune system and stresses the body.
Symptoms and complications of DKA include:
Cerebral edema, or brain swelling, is a rare but very dangerous complication that can result in coma, brain damage, or death. This is most common in children with DKA. Other serious complications from DKA include aspiration pneumonia, acute kidney injury, and adult respiratory distress syndrome.
Life-saving treatment uses rapid replacement of fluids with a salt (saline) solution followed by low-dose insulin and potassium replacement.
Ketoacidosis is a serious condition of glucose build-up in the blood and urine. A simple urine test can determine if high ketone levels are present.
Hyperglycemic hyperosmolar syndrome (HHS) is a serious complication of diabetes that involves a cycle of increasing blood sugar levels and dehydration, usually without increasing blood ketones. HHS usually occurs with type 2 diabetes. But it can also occur with type 1 diabetes. It is often triggered by a serious infection or another severe illness, or by medications that lower glucose tolerance or increase fluid loss (especially in people who are not drinking enough fluids).
Symptoms of HHS include high blood sugar levels, dry mouth, extreme thirst, dry skin, and high fever. HHS can lead to loss of consciousness, seizures, coma, and death.
Tight blood sugar (glucose) control increases the risk of low blood sugar (hypoglycemia). Hypoglycemia occurs if blood glucose levels fall below normal. It is generally defined as a blood sugar below 70 mg/dL, although this level may not necessarily cause symptoms in all patients.
Insufficient intake of food and excess exercise or alcohol intake may cause hypoglycemia. Usually the condition is manageable. Hypoglycemia can sometimes be severe or even life threatening, particularly if the patient fails to recognize the symptoms, especially while continuing to take insulin or other hypoglycemic drugs. Beta-blocking medications, which are often prescribed for high blood pressure and heart disease, can mask symptoms of hypoglycemia.
Specific risk factors for severe hypoglycemia include:
Hypoglycemia unawareness is a condition in which people become accustomed to hypoglycemic symptoms. They may no longer have any signs of hypoglycemia until the hypoglycemia becomes severe. It affects about 25% of patients who use insulin, nearly always people with type 1 diabetes. In such cases, hypoglycemia appears suddenly, without warning, and can escalate to a severe level.
Previous hypoglycemia is the biggest risk factor for hypoglycemic unawareness. Even a single recent episode of hypoglycemia may make it more difficult to detect the next episode. With vigilant monitoring and by rigorously avoiding low blood glucose levels, patients can often regain the ability to sense hypoglycemia symptoms. However, sometimes continuous glucose monitoring (CGM) is necessary to identify time periods when patients are hypoglycemic. CGM studies have shown that many people with type 1 diabetes are sometimes unaware that their blood sugars are very low.
Mild symptoms usually occur at moderately low and easily correctable levels of blood glucose. Not all patients have the same symptoms. Many people with diabetes come to recognize their hypoglycemia symptom pattern over time and it is usually consistent. Early symptoms can include:
Severely low blood glucose levels can cause neurologic symptoms, such as:
[For information on preventing hypoglycemia or managing an attack, see the Home Management section of this report.]
People with diabetes are more likely than non-diabetics to have heart problems, and to die from cardiovascular complications, including heart attack and stroke. Diabetes affects the heart in many ways:
Atherosclerosis is a disease of the arteries in which fatty material is deposited in the vessel wall, resulting in narrowing and eventual impairment of blood flow. Severely restricted blood flow in the arteries to the heart muscle leads to symptoms such as chest pain. Atherosclerosis shows no symptoms until a complication occurs.
Kidney disease (nephropathy) is a very serious complication of diabetes. With this condition, the tiny filters in the kidney (called glomeruli) become damaged and leak protein into the urine. Over time this can lead to kidney failure. Urine tests showing microalbuminuria (small amounts of protein in the urine) are important markers for kidney damage.
Diabetic nephropathy is the leading cause of end-stage renal disease (ESRD). Patients with ESRD have 13 times the risk of death compared to other patients with type 1 diabetes. If the kidneys fail, dialysis or transplantation is required. Symptoms of kidney failure may include swelling in the feet and ankles, itching, fatigue, and pale skin color. The outlook of end-stage renal disease has greatly improved during the last four decades for patients with type 1 diabetes, and fewer people with type 1 diabetes are developing ESRD.
Diabetes reduces or distorts nerve function, causing a condition called neuropathy. Neuropathy refers to a group of disorders that affect nerves. The two main types of neuropathy are:
Sensory neuropathy particularly affects the feet and legs. It is a common complication for people with type 1 or type 2 diabetes. The most serious consequences of neuropathy occur in the legs and feet and pose a risk for skin ulcers and infections in the bone and, in severe cases, amputation. Peripheral neuropathy usually starts in the toes and moves up the legs, and can also affect the fingers, hands and arms (called a stocking-glove distribution). Symptoms can include:
Autonomic neuropathy can cause:
Diabetic gastroparesis is a type of neuropathy that affects the digestive track. It is triggered by high blood sugar, which over time can damage the vagus nerve. The result of this damage is that the digestive system takes too long to move and digest food. Undigested food and the delay in stomach emptying can cause blood glucose levels to rise unpredictably, and make diabetes more difficult to control. Symptoms of gastroparesis include heartburn, nausea, abdominal bloating, feeling full after eating only a small amount of food, and vomiting of undigested food several hours after a meal. Gastroparesis generally only occurs in people who already have severe peripheral neuropathy. Patients with poorly-controlled blood sugars often have symptoms of gastroparesis, but this is reversible over weeks to months if blood glucose control improves.
Blood sugar control is an essential component in the treatment for neuropathy. Studies show that tight control of blood glucose levels delays the onset and slows progression of neuropathy. Heart disease risk factors may increase the likelihood of developing neuropathy. Lowering triglycerides, losing weight, reducing blood pressure, and quitting smoking may help prevent the onset of neuropathy.
About 15% of patients with diabetes have serious foot problems. They are the leading cause of hospitalizations for these patients. The consequences of both poor circulation and peripheral neuropathy make this a common and serious problem for all patients with diabetes. Diabetes is responsible for more than half of all lower limb amputations performed in the U.S. Most amputations start with foot ulcers.
People with diabetes who are overweight, smokers, and have a long history of diabetes tend to be at most risk. People who have the disease for more than 20 years and are taking insulin are at the highest risk. Related conditions that put people at risk include peripheral neuropathy, peripheral artery disease, foot deformities, and a history of ulcers.
Foot ulcers usually develop from minor injury that goes unnoticed because of neuropathy. Infections can sometimes make the ulcer worse and can involve muscle and bone. About one-third of foot ulcers occur on the big toe. Patients with diabetes and neuropathy should check their feet every night before going to bed to look for redness, blisters, or ulcers.
Charcot foot or Charcot joint (medically referred to as neuropathic arthropathy) is a degenerative condition that affects the bones and joints in the feet. It is associated with the nerve damage that occurs with neuropathy. Early changes appear similar to an infection, with the foot becoming swollen, red, and warm and can be caused by twisting the foot or ankle while walking or stepping off a stair. Gradually, the affected foot can become deformed. The joints may shift, change shape, and become unstable and bones can fracture over time.
Charcot foot typically develops in people who have neuropathy to the extent that they cannot feel sensation in the foot and are not aware of an existing injury. Instead of resting an injured foot or seeking medical help, the patient often continues normal activity, causing further damage.
Diabetes accounts for thousands of new cases of blindness annually and is the leading cause of new cases of blindness in adults ages 20 to 74. The most common eye disorder in diabetes is retinopathy. People with diabetes are also at higher risk for developing cataracts and certain types of glaucoma.
Retinopathy is a condition in which the retina becomes damaged. It generally occurs in one or two phases:
People with diabetes face a higher risk for influenza and its complications, including pneumonia. Everyone with diabetes should have annual influenza vaccinations and a vaccination against pneumococcal pneumonia.
Urinary Tract Infections
Women with diabetes face a significantly higher risk for urinary tract infections, which are likely to be more complicated and difficult to treat than in the general population.
Patients with diabetes are at increased risk for contracting the hepatitis B virus, which is transmitted through blood and other bodily fluids. Exposure to the virus can occur through sharing finger-stick devices or blood glucose monitors. Adults newly diagnosed with type 1 or type 2 diabetes should get hepatitis B vaccinations.
Diabetes doubles the risk for depression. Depression, in turn, may increase the risk for hyperglycemia and complications of diabetes.
Type 1 diabetes is associated with slightly reduced bone density, putting patients at risk for osteoporosis and possibly fractures.
Diabetes increases the risk for other conditions, including:
Diabetes can cause specific complications in women. Women with diabetes have an increased risk of recurrent yeast infections. In terms of sexual health, diabetes may cause decreased vaginal lubrication, which can lead to pain or discomfort during intercourse.
Women with diabetes should be aware that certain types of medication can affect their blood glucose levels. For example, birth control pills can raise blood glucose levels. Long-term use (more than 2 years) of birth control pills may increase the risk of certain health problems.
Diabetes and Pregnancy
Diabetes during pregnancy can increase the risk for birth defects. High blood sugar levels (hyperglycemia) can affect the developing fetus during the critical first 6 weeks of organ development. Women with diabetes (either type 1 or type 2) who are planning on becoming pregnant should strive to maintain good glucose control for 3 to 6 months before pregnancy.
It is also important for women to closely monitor their blood sugar levels during pregnancy. For women with type 1 diabetes, pregnancy can affect their insulin dosing needs. Insulin dosing may also need to be adjusted during and following delivery. [For more information, see "Treatment of Diabetes During Pregnancy" in the Treatment of Complications section of this report.]
Diabetes and Menopause
The changes in estrogen and other hormonal levels that occur during the transition to menopause (perimenopause) can cause major fluctuations in blood glucose levels. Women with diabetes also face an increased risk of premature menopause, which can lead to higher risk of heart disease.
Lack of Blood Glucose Control
Control of blood glucose levels is generally very poor in adolescents and young adults. Adolescents with diabetes are at higher risk than adults for ketoacidosis resulting from non-adherence with insulin management. Young people who do not control glucose are also at high risk for permanent damage in small blood vessels, such as those in the eyes. Many of these problems are made worse by the transition from pediatric care to adult medicine care. Many institutions have specific adolescent diabetes clinics to help to address this issue.
Up to a third of young women with type 1 diabetes have eating disorders and under-use insulin to lose weight. Anorexia and bulimia pose significant health risks in any young person. But they can be especially dangerous for people with diabetes.
There are 3 tests that can diagnose diabetes:
The fasting plasma glucose (FPG) test is the standard test for diagnosing diabetes. It is a simple blood test taken after 8 hours of fasting.
FPG levels indicate:
The FPG test is not always reliable, so a repeat test is recommended if the initial test suggests the presence of diabetes, or if the tests are normal in people who have symptoms or risk factors for diabetes. Widespread screening of patients to identify those at higher risk for diabetes type 1 is not recommended.
The oral glucose tolerance test (OGTT) is more complex than the FPG and may over-diagnose diabetes in people who do not have it. Some doctors recommend it as a follow-up after FPG, if the latter test results are normal. But the patient has symptoms or risk factors of diabetes. The test uses the following procedures:
OGTT glucose levels at 2 hours indicate:
Patients who have the FPG and OGTT tests must not eat for at least 8 hours prior to the test.
Any random blood glucose of 200 mg/dL or higher is also diagnostic of diabetes.
The oral glucose tolerance test is used to diagnose diabetes. The first portion of the test involves drinking a special glucose solution. Blood is then taken several hours later to test for the level of glucose in the blood. Patients with diabetes will have higher than normal levels of glucose in their blood.
This test examines blood levels of glycated hemoglobin, also known as hemoglobin A1c (HbA1c). The results are given in percentages and indicate a person's average blood glucose levels over the past 2 to 3 months. (The FPG and OGTT show a person's glucose level for only the time of the test.) The A1c test is not affected by recent food intake so patients do not need to fast to prepare for it.
In addition to providing information on blood sugar control and diabetes treatment, the A1c test may also be used as an alternative test for diagnosing diabetes.
A1c levels indicate:
A1c tests are also used to help patients with diabetes monitor how well they are keeping their blood glucose levels under control. For patients with diabetes, A1c is measured periodically up to every 2 to 3 months, or at least twice a year. While finger prick self-testing provides information on blood glucose for that moment, the A1c test shows how well blood sugar has been controlled overall for the past several months.
In general, most adult patients with diabetes should aim for A1c levels below or around 7%. Your doctor may adjust this goal depending on your individual health profile. An A1c target of under 7.5% is recommended for older healthy adults. Older adults with other health problems may need higher target levels of 8.0% to 8.5%.
Goal A1c levels for all children (under 18 years) are less than 7.5%. The American Diabetes Association no longer recommends various age-based A1c targets for children.
Schedule for A1c Monitoring:
The American Diabetes Association recommends that results from the A1c test be used to calculate estimated average glucose (eAG). EAG is a term that patients may see on lab results from their A1c tests. It converts the A1c percentages into the same mg/dL units that patients are familiar with from their daily home blood glucose tests. For example, an A1c of 7% suggests that the eAG is anywhere from 123 to 184 mg/dL with the most common average BG being 154 mg/dL.
The eAG terminology can help patients better interpret the results of their A1c tests, and make it easier to correlate A1c with results from home blood glucose monitoring.
Type 1 diabetes is characterized by the presence of a variety of antibodies that react against the islet cells. These antibodies are referred to as autoantibodies because they recognize the body's own cells, rather than a foreign invader. Blood tests for these autoantibodies can help differentiate between type 1 and type 2 diabetes. However, many patients with type 2 diabetes also have low levels of one or more autoantibodies and so autoantibodies may simply be the sign of damaged pancreatic islets beta cells. New tests for autoantibodies are being developed as research in this area continues.
Screening Tests for Heart Disease
All patients with diabetes should be tested for high blood pressure (hypertension) and unhealthy cholesterol and lipid levels and given an electrocardiogram. Other tests may be needed in patients with signs of heart disease.
Screening Tests for Kidney Damage
The earliest manifestation of kidney disease is microalbuminuria, in which tiny amounts of a key protein called albumin are found in the urine. Microalbuminuria is also a marker for other complications involving blood vessel abnormalities, including heart attack and stroke.
The American Diabetes Association recommends that people with diabetes receive an annual urine test for albumin. Patients should also have their blood creatinine tested at least once a year. Creatinine is a waste product that is removed from the blood by the kidneys. High levels of creatinine may indicate kidney damage. A doctor uses the results from a creatinine blood test to calculate the glomerular filtration rate (GFR). The GFR is an indicator of kidney function; it estimates how well the kidneys are cleaning the blood.
Screening for Retinopathy
The American Diabetes Association recommends that patients with type 1 diabetes have an annual comprehensive eye exam, with dilation, to check for signs of retina disease (retinopathy). Patients at low risk may need exams only every 2 to 3 years. Instead of a comprehensive eye exam, digital retinal photography may be used as a screening tool. Retinal photography uses a special type of camera to take images of the back of the eye.
Screening for Neuropathy
All patients should be screened for nerve damage (neuropathy), including an annual comprehensive foot exam. Patients who lose sensation in their feet should have a foot exam every 3 to 6 months to check for ulcers or infections. Patients should also be screened for intermittent claudication and peripheral artery disease (PAD) using the ankle-brachial index for diagnosis.
Good nutrition and regular physical activity can help prevent or manage medical complications of diabetes (such as heart disease and stroke), and help patients live longer and healthier lives. Nutrition and activity in many ways are the cornerstone of blood glucose control.
There is no single best diabetes diet. Patients should meet with a professional dietitian to plan an individualized diet within the general guidelines that takes into consideration their own health needs. Diabetes self-management education programs can also provide valuable nutritional advice.
The American Diabetes Association no longer advises a uniform ideal percentage of daily calories for carbohydrates, fats, or protein for all people with diabetes. Rather, these amounts should be individualized, based on your unique health profile. Carbohydrate counting is important for people with type 1 diabetes. They need to match their insulin doses to carbohydrate intake.
Healthy eating habits along with good control of blood glucose are the basic goals, and several good dietary methods are available to meet them. Recommended eating plans include Mediterranean, vegetarian, and lower-carbohydrate diets. What is most important is to find a healthy eating plan that works best for you and your lifestyle and food preferences. Whatever eating plan you follow, try to eat a variety of nutrient-rich food in appropriate portion sizes.
The American Diabetes Association's most recent nutritional guidelines recommend:
Weight gain is a potential side effect of intense diabetic control with insulin. Being overweight can increase the risk for health problems. The amount of weight gain caused by insulin is variable. Insulin is a growth factor and contribute to increase in weight of fat and muscle. On the other hand, studies suggest that more than one-third of women with diabetes omit or underuse insulin in order to lose weight. Eating disorders are especially dangerous in patients with diabetes and can increase the risk for diabetic ketoacidosis. Ketoacidosis is a significant complication of insulin depletion and can be life threatening.
Aerobic activity has significant and particular benefits for people with type 1 diabetes. It increases sensitivity to insulin, lowers blood pressure, improves cholesterol levels, and decreases body fat. Because glucose levels can swing dramatically during workouts, people with type 1 diabetes need to take certain precautions:
Avoid resistance or high impact exercises. They can strain weakened blood vessels in the eyes of patients with retinopathy. High-impact exercise may also injure blood vessels in the feet. Because patients with diabetes may have silent heart disease, they should always check with their providers before undertaking vigorous exercise.
Various fraudulent products are often sold on the Internet as "cures" or treatments for diabetes. These dietary supplements have not been studied or approved. The US Food and Drug Administration (FDA) and Federal Trade Commission (FTC) warn patients with diabetes not to be duped by bogus and unproven remedies.
According to the American Diabetes Association, there is no evidence to support herbal remedies or dietary supplements (including fish oil supplements) for the treatment of diabetes. There is no evidence that vitamin or mineral supplements can help people with diabetes who do not have underlying nutritional deficiencies.
Insulin is essential for control of blood glucose levels in type 1 diabetes. Good blood glucose control is the best way to prevent major complications in type 1 diabetes, including those that affect the kidneys, eyes, nerve pathways, and blood vessels. Intensive insulin treatment in early diabetes may even help preserve any residual insulin secretion for at least 2 years.
However, there are some significant problems with intensive insulin therapy.
A diet plan that compensates for insulin administration and supplies healthy foods is extremely important. Pancreas transplantation may eventually be considered for patients who cannot control glucose levels without frequent episodes of severe hypoglycemia.
The goal of intensive insulin therapy is to keep blood glucose levels as close to normal as possible, while avoiding episodes of hypoglycemia.
Blood glucose goals before meals (normal is less than 100 mg/dL
Peak postprandial goal: Less than 180 mg/dL for adults and children.
Blood glucose goals at bedtime:
For patients with type 2 diabetes, insulin therapy may consist of one or two daily insulin injections, one daily blood sugar test, and visits to the health care team every 3 months. However, for better control of blood glucose in type 1 diabetes, intensive management is usually required. The regimen is complicated although newer insulin forms may make it easier.
There are two components to insulin administration:
In achieving insulin control the patient must also take other steps:
Because of the higher risk for hypoglycemia in children, doctors recommend that intensive insulin treatment be used very cautiously in children under 13 and not at all in very young children.
Insulin cannot be taken orally because the body's digestive juices destroy it. Injections of insulin under the skin are the most common way to administer the medications (inhaled insulin has been available, but is used rarely). The timing and frequency of insulin injections depend upon a number of factors:
Rapid-Acting Analog Insulin
Insulin lispro (Humalog), insulin glulisine (Apidra) and insulin aspart (Novo Rapid, NovoLog) lower blood sugar very quickly. Insulin peaks 30 to 60 minutes after injection and continues to have some effect for about 4 hours. The short duration reduces the risk for hypoglycemic events after eating (postprandial hypoglycemia). Optimal timing for administering this insulin is about 15 minutes before a meal. But it can also be taken immediately after a meal (within 30 minutes) for patients with nausea or gastroparesis.
Regular insulin begins to act 30 minutes after injection, reaches its peak around 2 hours, and lasts about 6 to 8 hours. Regular insulin may be administered before a meal and may be better for high-fat meals. This insulin is not used as frequently for meal-time insulin.
NPH (Neutral Protamine Hagedorn) insulin is the standard intermediate form. It works within 2 to 4 hours, peaks 4 to 8 hours later, and lasts up to 14 hours. Lente (insulin zinc) is another intermediate insulin.
Long-acting basal insulins, such as insulin glargine (Lantus), and insulin detemir (Levemir) are released slowly. Long-acting insulin does not peak for most patients. It starts working in 2 to 4 hours and lasts as long as 24 hours (glargine) or 18 hours (detemir). New types of long-acting insulins are now available including one called degludec that last longer than 24 hours.
Regimens generally include both rapid-acting and basal insulins to try to match the natural insulin secretion. Often basal insulin is injected once or twice a day (about 12 hours apart). Rapid-acting analog insulin is taken before every meal and sometimes with larger snacks. Combination of two types of insulin combined in one injection are available This can reduce the number of injections, but makes the dosing less adjustable and often make good blood glucose control difficult except for patients with very regimented daily schedules.
Insulin pens, which contain cartridges of insulin, have been available for some time, although they are still more expensive than vials of insulin. These prefilled disposable pens, are more portable, do not carry the stigma of a syringe, and are easier and more convenient for patients. It is often easier for people to take meal-time insulin when they are away from home. For people with type 1 diabetes taking small amounts of insulin using insulin pens may cause less waste as pens contain only 300u of insulin while a vial contains 1000u of insulin.
Afrezza, an inhaled form of fast-acting insulin. Afrezza is taken before meals and is designed for adult patients who need mealtime insulin to help control hyperglycemia in between meals. The ability to adjust dosage is limited with inhaled insulin. Afrezza is not a substitute for long-acting insulin. Patients with type 1 diabetes must use it in combination with a long-acting insulin. Afrezza should not be used by patients who smoke or those with chronic lung diseases such as asthma or COPD.
The FDA will continue to examine whether Afrezza increases the risk for lung impairment or cancer, and whether it is appropriate for children. A previous inhaled insulin was withdrawn from the market because of changes in lung function and modest patient interest.
An insulin pump can improve blood glucose control and quality of life with fewer hypoglycemic episodes than multiple injections. The pumps correct for the "dawn phenomenon" (sudden rise of blood glucose in the morning) and allow quick reductions for specific situations, such as exercise. A number of different brands are available.
The typical pump is about the size of a pager and has a digital display. Some are worn externally and are programmed to deliver insulin through a catheter under the skin. They generally use rapid-acting insulin, the most predictable type. They work by administering a small amount of insulin continuously (the basal rate) and a higher dose (a bolus dose) when food is eaten.
Although learning to use the pump can be complicated at first, most patients find over time that the devices are fairly easy to use. Adults, adolescents, and school children use insulin pumps and even very young children (ages 2 to 7 years) are able to successfully use them.
The catheter at the end of the insulin pump is inserted through a needle into the abdominal fat of a person with diabetes. Dosage instructions are entered into the pump's small computer, and the appropriate amount of insulin is then injected into the body in a calculated, controlled manner.
To achieve good blood sugar control, patients and parents of children must undergo some training. The patient and doctor must determine the amount of insulin used. It is not automatically calculated. This requires an initial learning period, including understanding insulin needs over the course of the day and in different situations (before exercise and driving) and knowledge of carbohydrate counting. Frequent blood testing is very important, particularly during the training period.
Insulin pumps are more expensive than insulin shots and occasionally have some complications, such as blockage in the device or skin irritation at the infusion site. Despite early concerns, pumps do not appear to increase the risk of ketoacidosis.
The main advantages of insulin pump use are the ability to adjust basal rates during the day, the bolus wizard which helps calculate the right dose of insulin to match a meal, not having to carry separate supplies, and the ability to combine the pump with a continuous glucose monitoring sensor that can give warnings and alerts. Despite certain challenges, research continues to progress on a "closed-loop" system that combines an insulin pump (and often a pump with a different hormone called glucagon) with a continuous glucose meter to form an artificial pancreas.
Pramlintide (Symlin) is an injectable drug that is used to help control postprandial hyperglycemia, the sudden increase in blood sugar after a meal. Pramlintide is injected before meals and can help lower blood sugar levels in the 3 hours after meals. Pramlintide is used in addition to insulin for patients who take insulin regularly, but still need better blood sugar control. Pramlintide and insulin are the only two drugs approved for treatment of type 1 diabetes. Pramlintide is indicated only for adults.
Pramlintide is a synthetic form of amylin, a hormone that is related to insulin. Side effects may include nausea, vomiting, abdominal pain, headache, fatigue, and dizziness. Patients with type 1 diabetes have an increased risk of severe low blood sugar (hypoglycemia) that may occur within 3 hours following a pramlintide injection. This drug should not be used if patients have trouble knowing when their blood sugar is low or have slow stomach emptying (gastroparesis).
Metformin (Glucophage, generic) is an oral medication used commonly in patients with type 2 diabetes. However, some patients with type 1 diabetes may be (or become) overweight or obese and are relatively insulin-resistant. Metformin can decrease insulin needs and prevent weight gain in patients with insulin resistance.
Liraglutide (Victoza) is an injectable medication used frequently in people with type 2 diabetes. This medication has also been used in people with type 1 diabetes and research studies are still evaluating the benefits of this medication in these patients.
All patients with diabetes and high blood pressure should adopt lifestyle changes. These include weight reduction (when needed), following the Dietary Approaches to Stop Hypertension (DASH) or similar diet, smoking cessation, limiting alcohol intake, and limiting salt intake to no more than 1500 to 2300 mg of sodium per day. (Exact sodium limits are determined on an individual basis; discuss with your doctor what an appropriate sodium limit is for you.)
High Blood Pressure Control
In general, people with diabetes should strive for blood pressure levels of less than 140/90 mm Hg (systolic/diastolic). For some people, especially younger patients, a systolic blood pressure goal of 130 mm Hg may be appropriate. Lowering systolic blood pressure below 130 mm Hg has not been found to provide added benefit. Lowering diastolic below 70 may cause harm.
Patients with diabetes and high blood pressure need an individualized approach to drug treatment, based on their particular health profile. Dozens of anti-hypertensive drugs are available. The most beneficial fall into the following categories:
Nearly all patients who have diabetes and high blood pressure should take an ACE inhibitor (or ARB) as part of their regimen for treating their hypertension. These drugs help prevent heart and kidney damage, and are recommended as the best first-line drugs for people with diabetes and hypertension. The most common side effect of ACE inhibitors is a chronic dry cough. An angiotensin-receptor blocker (ARB) is recommended for patients who cannot tolerate ACE inhibitors.
Improving Cholesterol and Lipid Levels
Abnormal cholesterol and lipid levels are common in diabetes. High LDL ("bad") cholesterol should always be lowered. But people with diabetes also often have additional harmful imbalances, including low HDL ("good") cholesterol and high triglycerides.
In general, adult patients should aim for LDL levels below 100 mg/dL, HDL levels over 50 mg/dL, and triglyceride levels below 150 mg/dL. The American Diabetes Association considers statin therapy for lowering LDL levels appropriate for most patients with type 1 diabetes who are 40 to 75 years old. For patients younger than age 40, statin therapy needs to be considered on an individual basis.
Lifestyle changes for cholesterol management in patients with diabetes focus on:
For medications, statins are the best cholesterol-lowering drugs. They include atorvastatin (Lipitor, generic), lovastatin (Mevacor, generic), pravastatin (Pravachol, generic), simvastatin (Zocor, Simcor, Vytorin, and generics), fluvastatin (Lescol, generic), rosuvastatin (Crestor), and pitavastatin (Livalo).
These drugs are very effective for lowering LDL cholesterol levels. However, they may increase blood glucose levels in some patients, especially when taken in high doses. Still, statin drugs are considered generally safe. If one statin drug does not work or has side effects, the doctor may recommend switching to a different statin.
The primary safety concern with statins has involved myopathy, an uncommon condition that can cause muscle damage and, in some cases, muscle and joint pain. A routine blood test for creatine kinase can monitor for this side effect. A specific myopathy called rhabdomyolysis can lead to kidney failure. People with diabetes and risk factors for myopathy should be monitored for muscle symptoms.
Ezetimibe may be used in combination with a statin drug for those with recent acute coronary syndrome. A new type of medication called a PCSK9 inhibitor is now available to reduce cholesterol levels in patients with genetic causes of high cholesterol levels. This medication is given as an injection under the skin.
Aspirin for Heart Disease Prevention
For patients with diabetes who have additional heart disease risk factors, taking a daily aspirin can reduce the risk for blood clotting and may help protect against heart attacks. (There is not enough evidence to indicate that aspirin prevention is helpful for patients at lower risk.) These risk factors include a family history of heart disease, high blood pressure, smoking, unhealthy cholesterol levels, or excessive urine levels of the protein albumin. The recommended dose is 75 to 162 mg/day. Talk to your doctor, particularly if you are at risk for aspirin side effects such as gastrointestinal bleeding and ulcers.
Patients with severe diabetic retinopathy or macular edema (swelling of the retina) should see an eye specialist who is experienced in the management and treatment of diabetic retinopathy. Once damage to the eye develops, laser or photocoagulation eye surgery may be needed. Laser surgery can help reduce vision loss in high-risk patients. Drug therapy with anti-vascular endothelial growth factor (VEGF) is also recommended for treatment of diabetic macular edema.
About a third of foot ulcers will heal within 20 weeks with good wound care treatments. Some treatments are as follows:
Other Treatments for Foot Ulcers
Doctors are also using or investigating other treatments to heal ulcers. These include:
The only FDA-approved drugs for treating neuropathy are pregabalin (Lyrica) and duloxetine (Cymbalta). Other drugs and treatments are used on an off-label basis.
The American Academy of Neurology's (AAN) guidelines for treating painful diabetic neuropathy recommend:
Treatments for Other Complications of Neuropathy
Neuropathy also impacts other functions, and treatments are needed to reduce their effects. If diabetes affects the nerves in the autonomic nervous system, then abnormalities of blood pressure control and bowel and bladder function may occur. Erythromycin, domperidone (Motilium), or metoclopramide (Reglan) may be used to relieve delayed stomach emptying caused by neuropathy (diabetic gastroparesis). Patients need to watch their nutrition if the problem is severe.
Erectile dysfunction is also associated with neuropathy. Studies indicate that phosphodiesterase type 5 (PDE-5) drugs, such as sildenafil (Viagra), vardenafil (Levitra), tadalafil (Cialis), and avanafil (Stendra) are safe and effective, at least in the short term, for many patients with diabetes. Typical side effects are minimal but may include headache, flushing, and upper respiratory tract and flu-like symptoms. Patients who take nitrate medications for heart disease cannot use PDE-5 drugs. Recent studies have shown that testosterone replacement may also improve erectile function in older patients that have low testosterone levels in the blood.
Tight control of blood sugar and blood pressure is essential for preventing the onset of kidney disease and for slowing the progression of the disease.
ACE inhibitors are the best class of blood pressure medications for delaying kidney disease and slowing disease progression in patients with diabetes. Angiotensin-receptor blockers (ARBs) are also very helpful.
Anemia is a common complication of end-stage kidney disease. Patients on dialysis usually need injections of erythropoiesis-stimulating drugs to increase red blood cell counts and control anemia. However, these drugs -- darbepoetin alfa (Aranesp) and epoetin alfa (Epogen and Procrit) -- can increase the risk of blood clots, stroke, heart attack, and heart failure in patients with end-stage kidney disease when they are given at higher than recommended doses.
End-stage kidney disease, anemia, and treatment with medications that mimic erythropoietin change the relationship between A1c and blood glucose. In this situation, the A1c is not a reliable indicator of good glucose control. Patients with end-stage kidney disease are often at greater risk of hypoglycemia, especially fasting hypoglycemia during the night or early morning. Patients with kidney disease taking insulin to control their blood sugars often need to reduce their insulin doses as their kidney disease progresses. Other tests such as fructosamine can be used to monitor blood sugar control instead of A1c.
The FDA recommends that patients with end-stage kidney disease who receive erythropoiesis-stimulating drugs should:
Some recommendations for preventing pregnancy complications include:
Both low blood sugar (hypoglycemia) and high blood sugar (hyperglycemia) are of concern for patients who take insulin. It is important, therefore, to carefully monitor blood glucose levels. In general, patients with type 1 diabetes need to take readings four or more times a day.
The American Diabetes Association recommends that people on multiple dose insulin should test their blood sugar:
Patients should aim for the following measurements:
Different goals may be required for specific individuals, including pregnant women, very old and very young people, and those with accompanying serious medical conditions.
A typical blood sugar test includes the following:
Home monitors are less accurate than laboratory monitors and many do not meet the standards of the American Diabetes Association. However, they are usually accurate enough to indicate when blood sugar is too low.
To monitor the amount of glucose within the blood, a person with diabetes should test their blood regularly. The procedure is quite simple and can often be done at home.
Some simple procedures may improve accuracy, such as:
Continuous glucose monitoring systems (CGMs) use a small plastic sensor inserted under the skin of the abdomen to monitor glucose levels every 5 minutes. Depending on the system, CGMs measure glucose levels for 3 to 7 days and sound an alarm if glucose levels are too high or low. These devices are used in addition to traditional finger-stick testing and glucose meters. But these devices do not replace them. Some CGM systems are now approved for children as well as adults. The American Diabetes Association recommends continuous glucose monitoring as a useful tool for patients with type 1 diabetes.
Urine tests are useful for detecting the presence of ketones. These tests should always be performed during illness or stressful situations, when diabetes is likely to go out of control. The patient should also undergo yearly urine tests for microalbuminuria (small amounts of protein in the urine), a risk factor for future kidney disease. Tests for sugar in the urine are no longer used to diagnose diabetes or monitor therapy.
The following tips may help avoid hypoglycemia or prepare for attacks.
Family and friends should be aware of the symptoms and be prepared.
Patients with type 1 diabetes should always wear a medical alert ID bracelet or necklace that states that they have type 1 diabetes and take insulin.
Measures to Prevent Foot Ulcers
Preventive foot care can significantly reduce the risks of ulcers and amputation. Some tips for preventing problems include:
Researchers continue to investigate islet-cell transplantation as a way to help patients no longer be dependent on insulin or reduce their use of insulin.
This procedure has been used mostly in clinical trials. But it has helped patients with severe type 1 diabetes to become free of insulin injections. However, many of these insulin-independent patients needed to resume insulin injections within a few years. Researchers are continuing to work on refining the transplantation protocols so that benefits can be more sustainable and long lasting.
A major obstacle for the islet cell transplantation is that every transplantation needs islets from two or more deceased donors to supply sufficient islet cells. Because the number of donors in many countries remains low, this procedure is only feasible for a very small percentage of patients with type 1 diabetes.
Researchers are looking for alternative approaches, including the use of umbilical cord cells, embryonic or adult stem cells, bone marrow transplantation, and other types of cellular therapies. These studies are still in very early stages. But researchers predict that there will be major advances in these fields in the coming years.
Most pancreas transplants use a cadaver pancreas from a deceased donor. There are three main types of cadaver pancreas transplants:
A fourth option, which is much less commonly performed, is for the patient to receive a partial pancreas from a living donor (typically a relative). This type of transplant may be performed at the same time as a living donor kidney transplant. Sometimes islet cells from the pancreas may be transplanted.
Survival rates are best for simultaneous pancreas-kidney transplants and are worst for pancreas-alone transplants.
Organ transplantation can have significant surgical and post-surgical complications. In addition, to prevent organ rejection, patients need to take immunosuppressive drugs on a lifelong basis following a transplant. Doctors generally recommend transplants in cases of end-stage kidney failure or when diabetes poses more of a threat to the patient's life than the transplant itself.
Uncontrolled diabetes causes damage to many tissues of the body, including the kidneys. Kidney damage caused by diabetes most often involves thickening and hardening of the internal kidney structures. Strict blood glucose control may delay the progression of diabetic kidney disease.
American Diabetes Association. (7) Approaches to glycemic treatment. Diabetes Care. 2015 Jan;38 Suppl:S41-S48. PMID: 25537707 www.ncbi.nlm.nih.gov/pubmed/25537707.
Atkinson, MA. Type 1 diabetes mellitus. In: Melmed S, Polonsky KS, Larsen PR, Kronenberg HM, eds. Williams Textbook of Endocrinology. 13th ed. Philadelphia, PA: Elsevier; 2016:chap 32.
Brownlee M, Aiello LP, Cooper ME, Vinik AI, Plutzky J,Boulton AJM. Complications of diabetes mellitus. In: Melmed S, Polonsky KS, Larsen PR, Kronenberg HM, eds. Williams Textbook of Endocrinology. 13th ed. Philadelphia, PA: Elsevier; 2016:chap 33.
Cameron FJ, Wherrett DK. Care of diabetes in children and adolescents: controversies, changes, and consensus. Lancet. 2015 May 23;385(9982):2096-2106. Review. PMID: 26009230 www.ncbi.nlm.nih.gov/pubmed/26009230.
Chamberlain JJ, Rhinehart AS, Shaefer CF Jr, Neuman A. Diagnosis and management of diabetes: Synopsis of the 2016 American Diabetes Association Standards of Medical Care in Diabetes. Ann Intern Med. 2016 Apr 19;164(8):542-552. Epub 2016 Mar 1. PMID: 26928912 www.ncbi.nlm.nih.gov/pubmed/26928912.
Chiang JL, Kirkman S, Laffel LMB, Peters AL. Type 1 diabetes through the life span: a position statement of the American Diabetes Association. Diabetes Care. Epub 16 Jun 2014.
DCCT/EDIC Research Group, Aiello LP, Sun W, et al. Intensive diabetes therapy and ocular surgery in type 1 diabetes. N Engl J Med. 2015 Apr 30;372(18):1722-1733. PMID: 25923552 www.ncbi.nlm.nih.gov/pubmed/25923552.
de Ferranti SD, de Boer IH, Fonseca V, et al. Type 1 diabetes mellitus and cardiovascular disease: a scientific statement from the American Heart Association and American Diabetes Association. Circulation. 2014 Sep 23;130(13):1110-1130. Epub 2014 Aug 11. Review. PMID: 25114208 www.ncbi.nlm.nih.gov/pubmed/25114208.
Evert AB, Boucher JL, Cypress M, et al. Position statement: Nutrition therapy recommendations for the management of adults with diabetes. Diabetes Care. 2013;36(11):3821-3842.
Lipsky BA, Berendt AR, Cornia PB, et al. 2012 Infectious Diseases Society of America clinical practice guideline for the diagnosis and treatment of diabetic foot infections. Clin Infect Dis. 2012;54(12):e132-e173.
Margolis DJ, Gupta J, Hoffstad O, et al. Lack of effectiveness of hyperbaric oxygen therapy for the treatment of diabetic foot ulcer and the prevention of amputation: a cohort study. Diabetes Care. 2013 Jul;36(7):1961-1966. PMID: 23423696 www.ncbi.nlm.nih.gov/pubmed/23423696.
Nathan DM. Diabetes: advances in diagnosis and treatment. JAMA. 2015 Sep 8;314(10):1052-1062. Review. PMID: 26348754 www.ncbi.nlm.nih.gov/pubmed/26348754.
Pillay J, Armstrong MJ, Butalia S, et al. Behavioral programs for type 1 diabetes mellitus: A systematic review and meta-analysis. Ann Intern Med. 2015 Dec 1;163(11):836-847. Epub 2015 Sep 29. Review. PMID: 26414020 www.ncbi.nlm.nih.gov/pubmed/26414020.
Rewers MJ, Pillay K, de Beaufort C, et al. ISPAD clinical practice consensus guidelines 2014. Assessment and monitoring of glycemic control in children and adolescents with diabetes. Pediatr Diabetes. 2014 Sep;15 Suppl 20:102-114. PMID 25182311 www.ncbi.nlm.nih.gov/pubmed/25182311.
Reviewed By: Brent Wisse, MD, Associate Professor of Medicine, Division of Metabolism, Endocrinology & Nutrition, University of Washington School of Medicine, Seattle, WA. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team