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This summary covers the research on the benefits and possible side effects of medicines to lower or control your blood sugar. It will help you talk with your doctor or other health care professional to decide which medicines are best for you.

PubMed Health. A service of the National Library of Medicine, National Institutes of Health.

A.D.A.M. Medical Encyclopedia [Internet]. Atlanta (GA): A.D.A.M.; 2013.

A.D.A.M. Medical Encyclopedia.

Diabetes

Last reviewed: August 5, 2014.

Diabetes is a chronic disease in which the body cannot regulate the amount of sugar in the blood.

Causes

Insulin is a hormone produced by the pancreas to control blood sugar. Diabetes can be caused by too little insulin resistance to insulin, or both.

To understand diabetes, it is important to first understand the normal process by which food is broken down and used by the body for energy. Several things happen when food is digested:

  • A sugar called glucose enters the bloodstream. Glucose is a source of fuel for the body.
  • An organ called the pancreas makes insulin. The role of insulin is to move glucose from the bloodstream into muscle, fat, and liver cells, where it can be stored or used as fuel.
Food and insulin release

People with diabetes have high blood sugar because their body cannot move sugar from the blood into muscle and fat cells to be burned or stored for energy, and because their liver makes too much glucose and releases it into the blood. This is because either:

There are two major types of diabetes. The causes and risk factors are different for each type:

Type I diabetes
  • Type 1 diabetes can occur at any age, but it is most often diagnosed in children, teens, or young adults. In this disease, the body makes little or no insulin. This is because the pancreas cells that make insulin stop working. Daily injections of insulin are needed. The exact cause is unknown.
  • Type 2 diabetes is much more common. It most often occurs in adulthood, but because of high obesity rates, teens and young adults are now being diagnosed with this disease. Some people with type 2 diabetes do not know they have it.
  • There are other causes of diabetes, and some patients cannot be classified as type 1 or type 2.

Gestational diabetes is high blood sugar that develops at any time during pregnancy in a woman who does not have diabetes.

If your parent, brother, or sister has diabetes, you may be more likely to develop the disease.

If you eat too much sugar over a long time, you may develop type 2 diabetes.The correct answer is false. Diabetes is caused by a problem in the way your body makes or uses the hormone insulin. Insulin helps move blood sugar (glucose) into cells, where it is stored to be used for energy. Eating too much sugar won't cause diabetes. But it may make you overweight, which can put you at risk for diabetes.Being overweight makes it harder for your body to properly use insulin.The correct answer is true. Extra fat in the body makes it harder for the body to use insulin properly. This is called insulin resistance. Losing excess weight and being active can help prevent or reverse insulin resistance.Which of the following health conditions does NOT put you at risk for type 2 diabetes?The correct answer is asthma. All of the other conditions increase your risk for diabetes. If you have any of these conditions, work with your doctor to control your risk factors for diabetes and heart disease.You can have diabetes for years and not know it.The correct answer is true. That's why it's important to talk with your doctor about whether you should have diabetes screening tests. People with high blood pressure, who are over age 45, and those who are overweight and have other risk factors should consider being tested for diabetes.What are early symptoms of type 2 diabetes?The correct answer is all of the above. If you notice any of these symptoms, talk with your doctor.If you have a blood sugar level higher than ____ , your doctor may test you for diabetes.The correct answer is 200 mg/dL. If your blood sugar is at this level, your doctor may give you these tests to confirm that you have diabetes: Fasting blood glucose level -- diabetes: higher than 126 mg/dL 2 times, Hemoglobin A1c test -- diabetes: 6.5% or higher, Oral glucose tolerance test -- diabetes: higher than 200 mg/dL after 2 hoursWhat health care problems are caused by diabetes?The correct answer is all of the above. Over time, too much sugar in the blood can harm your eyes, kidneys, nerves, skin, heart, and blood vessels. Talk with your doctor about the best ways to keep your blood sugar, blood pressure, and cholesterol level in a healthy range.What are treatments for type 2 diabetes?The correct answer is all of the above. The main treatment for type 2 diabetes is diet and exercise. If you still have trouble managing your blood sugar level, you may need medicine or insulin. Work with your health care provider to learn how much fat, protein, and carbohydrates you need in your diet.If you have type 2 diabetes, you will have to inject insulin.The correct answer is maybe. Many people can control type 2 diabetes with diet and exercise and diabetes medicines if needed. However, if your blood sugar remains uncontrolled, you may need to inject insulin.Having diabetes increases your risk for heart disease.The correct answer is true. Diabetes directly affects your heart, plus it makes it hard to control cholesterol. This can lead to heart disease and other problems. A healthy diet, regular exercise, and eating less salt can help control diabetes, blood pressure, and cholesterol. This will reduce your risk of heart disease.Some people with diabetes no longer need medicine if they lose weight and exercise.The correct answer is true. Some people with type 2 diabetes no longer need medicine if they lose weight and become more active. When they reach their ideal weight, their body's own insulin and a healthy diet can control their blood sugar levels.

Symptoms

A high blood sugar level can cause several symptoms, including:

  • Blurry vision
  • Excess thirst
  • Frequent urination
  • Hunger
  • Weight loss

Because type 2 diabetes develops slowly, some people with high blood sugar have no symptoms.

Symptoms of type 1 diabetes develop over a short period. People may be very sick by the time they are diagnosed.

After many years, diabetes can lead to other serious problems. These problems are known as diabetes complications, and include:

  • Eye problems, including trouble seeing (especially at night), light sensitivity, and blindness
  • Sores and infections of the leg or foot, which untreated can lead to amputation of the leg or foot
  • Damage to nerves in the body, causing pain, tingling, a loss of feeling, problems digesting food, and erectile dysfunction
  • Kidney problems, which can lead to kidney failure
  • Weakened immune system, which can lead to more frequent infections
  • Increased chance of having a heart attack or stroke
Diabetic retinopathy

Exams and Tests

A urine analysis may show high blood sugar. But a urine test alone does not diagnose diabetes.

Your health care provider may suspect that you have diabetes if your blood sugar level is higher than 200 mg/dL. To confirm the diagnosis, one or more of the following tests must be done.

Blood tests:

  • Fasting blood glucose level -- diabetes is diagnosed if the fasting glucose level is higher than 126 mg/dL on two different tests. Levels between 100 and 126 mg/dL are called impaired fasting glucose or pre-diabetes. These levels are risk factors for type 2 diabetes.
  • Hemoglobin A1c (A1C) test --
    • Normal: Less than 5.7%
    • Pre-diabetes: 5.7% - 6.4%
    • Diabetes: 6.5% or higher
  • Oral glucose tolerance test -- diabetes is diagnosed if the glucose level is higher than 200 mg/dL 2 hours after drinking a sugar drink. (This test is used more often for type 2 diabetes.)

Screening for type 2 diabetes in people who have no symptoms is recommended for:

  • Overweight children who have other risk factors for diabetes, starting at age 10 and repeated every 3 years
  • Overweight adults (BMI of 25 or higher) who have other risk factors
  • Adults over age 45, repeated every 3 years

Treatment

Type 2 diabetes may be reversed with lifestyle changes, especially losing weight with exercise and by eating healthier foods. Some cases of type 2 diabetes can also be improved with weight loss surgery.

There is no cure for type 1 diabetes.

Treating either type 1 diabetes or type 2 diabetes involves medicines, diet, and exercise to control blood sugar level.

Getting better control over your blood sugar, cholesterol, and blood pressure levels helps reduce the risk of kidney disease, eye disease, nervous system disease, heart attack, and stroke.

To prevent diabetes complications, visit your health care provider at least two to four times a year. Talk about any problems you are having. Follow your health care provider's instructions on managing your diabetes.

Support Groups

Many resources can help you understand more about diabetes. If you have diabetes, you can also learn ways to manage your condition and prevent diabetes complications.

Prevention

Keeping an ideal body weight and an active lifestyle may prevent or delay the start of type 2 diabetes.

Type 1 diabetes cannot be prevented.

References

  1. American Diabetes Association. Standards of medical care in diabetes -- 2014. Diabetes Care. 2014; Jan;34 Suppl 1:S14-S80. [PubMed: 24357209]
  2. Buse JB, Polonsky KS, Burant CF. Type 2 diabetes mellitus. In: Kronenberg HM, Melmed S, Polonsky KS, Larsen PR. Williams Textbook of Endocrinology. 12th ed. Philadelphia, PA: Saunders Elsevier; 2011:chap 31.
  3. Eisenbarth GS, Buse JB. Type 1 diabetes mellitus. In: Kronenberg HM, Melmed S, Polonsky KS, Larsen PR. Williams Textbook of Endocrinology. 12th ed. Philadelphia, PA: Saunders Elsevier; 2011:chap 32.

Review Date: 8/5/2014.

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.

A.D.A.M., Inc. is accredited by URAC, also known as the American Accreditation HealthCare Commission (www.urac.org). URAC's accreditation program is an independent audit to verify that A.D.A.M. follows rigorous standards of quality and accountability. A.D.A.M. is among the first to achieve this important distinction for online health information and services. Learn more about A.D.A.M.'s editorial policy, editorial process and privacy policy. A.D.A.M. is also a founding member of Hi-Ethics and subscribes to the principles of the Health on the Net Foundation (www.hon.ch).

The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed medical professional should be consulted for diagnosis and treatment of any and all medical conditions. Call 911 for all medical emergencies. Links to other sites are provided for information only — they do not constitute endorsementscof those other sites. © 1997–2011 A.D.A.M., Inc. Any duplication or distribution of the information contained herein is strictly prohibited.

Copyright © 2013, A.D.A.M., Inc.

A.D.A.M., Inc. is accredited by URAC, also known as the American Accreditation HealthCare Commission (www.urac.org). URAC's accreditation program is an independent audit to verify that A.D.A.M. follows rigorous standards of quality and accountability. A.D.A.M. is among the first to achieve this important distinction for online health information and services. Learn more about A.D.A.M.'s editorial policy, editorial process and privacy policy. A.D.A.M. is also a founding member of Hi-Ethics and subscribes to the principles of the Health on the Net Foundation (www.hon.ch).

The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed medical professional should be consulted for diagnosis and treatment of any and all medical conditions. Call 911 for all medical emergencies. Links to other sites are provided for information only — they do not constitute endorsementscof those other sites. © 1997–2011 A.D.A.M., Inc. Any duplication or distribution of the information contained herein is strictly prohibited.

Copyright © 2013, A.D.A.M., Inc.

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Figures

  • Endocrine glands.
    Diabetic retinopathy.
    Islets of Langerhans.
    Pancreas.
    Insulin pump.
    Type I diabetes.
    Diabetic blood circulation in foot.
    Food and insulin release.
    Insulin production and diabetes.

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