What causes diabetes?

No one knows what causes diabetes, but scientists are working hard to find out. There are three major types of diabetes: Type 1, Type 2, and Gestational. Type 1 diabetes usually develops in children, teenagers or young adults. Scientists believe this is a genetically caused condition and is not related to lifestyle habits. Gestational diabetes occurs during pregnancy and usually disappears after the baby is born.

Pre-diabetes is a condition people usually have before they develop Type 2 diabetes. People with pre-diabetes have higher than normal blood sugar, but not high enough to be considered diabetic. Research shows people with pre-diabetes can prevent or delay diabetes by changing their lifestyle: by eating healthy foods, losing weight, and staying physically active. This is good news and gives us hope that we can win the fight against diabetes. But we have a long way to go. We know that out of every 10 people in South Carolina, six are overweight, six have high blood pressure, four get little or no exercise, and three have high cholesterol. The more healthy choices we make, the less diabetes we’ll have.

Type 1 Diabetes

  • Your body stops making insulin or makes only a tiny bit.
  • Treatment: Under your doctor’s care, take insulin by needle or pump every day, eat healthy foods, exercise regularly, and monitor blood sugar, blood pressure and cholesterol.
  • Cause: Scientists think people with certain genes develop something in their bodies that attacks the cells that make insulin or the insulin itself.
  • Risk: This is a rare type of diabetes. For every 10 people with diabetes, only one has Type 1. It happens more often to children and teenagers than adults. It strikes white people more than people of color.
  • Prevention: Researchers are trying to learn if Type 1 diabetes can be prevented.
  • Formerly called: Insulin-dependent diabetes mellitus (IDDM) or juvenile-onset diabetes.
To learn more:
Juvenile Diabetes Research Foundation International
Diabetes information for children, teens, parents, and people who have friends or family with diabetes. Learn about managing diabetes at home, at school, and in your everyday life. Parents can find tips on how to help your child live with diabetes..
Diabetes Type 1
(National Library of Medicine)
Diabetes Type 1 from MEDLINEplus. Lists and links reviewed by medical libraries.
Children with DIABETES: The on-line community for kids, families and adults with diabetes.

Type 2 Diabetes

  • Your body does not make enough insulin or your body does not use it, or both.
  • Treatment: Eat the right amount of healthy food, get regular physical activity, take the medicines your doctor prescribes, and check your blood sugar, blood pressure and cholesterol. Some people take diabetes pills or insulin shots.
  • Cause: Experts don't know what causes Type 2 diabetes. They do know it is not caused by eating too many sweets. Type 2 diabetes tends to run in families and in overweight people.
  • Risk: It's the most common type of diabetes. For every 10 people with diabetes, nine will have Type 2. Most people are in their 30s or 40s when they learn they have Type 2 diabetes, but children and the elderly can develop it. You are more likely to develop Type 2 diabetes if you have a family history of diabetes, don’t exercise, or weigh too much. It is also more likely if you are of African American, Native American, Hispanic, or Asian/Pacific Islander heritage. You are also more likely to develop Type 2 diabetes if you had diabetes during pregnancy. The number of young people developing Type 2 diabetes is growing rapidly. This is because they don’t eat healthy foods or exercise and because they are overweight.
  • Prevention: You can prevent or delay Type 2 diabetes by eating healthy, losing weight (if overweight) and by doing daily physical activity or regular exercise.
  • Formerly called: Non-insulin dependent diabetes mellitus (NIDDM) or adult-onset diabetes. These names were confusing. so we now simply say "Type 2 diabetes." Some people with Type 2 diabetes must take insulin; however, they still have Type 2 diabetes (not Type 1).
To learn more:
American Diabetes Association
Type 2 diabetes information from the American Diabetes Association. Select All About Diabetes from the navigation bar on the left. Look for Type 2 Diabetes.
Links to sites which have been reviewed by medical librarians at the National Library of Medicine.


  • Your body has higher than normal glucose levels, but not high enough to be called diabetes. Your body is trying to control the glucose levels, but is failing. You are at high risk for developing Type 2 diabetes. You might or might not have symptoms of diabetes.
  • Treatment: Lose weight, eat healthy foods and get moderate regular exercise.
  • Cause: Nobody knows if pre-diabetes can be prevented.
  • Risk: Overweight people age 45 and older, especially if they already have some risk factors for diabetes.
  • Prevention: Experts don’t know if pre-diabetes can be prevented, but research shows that diabetes can be prevented or delayed by eating healthy foods, losing weight (if overweight) and by getting moderate regular exercise.
  • Also called: Impaired Fasting Glucose (IFG) or Impaired Glucose Tolerance (IGT)
To learn more:
American Diabetes Association
On the ADA site, select All About Diabetes from the menu on the left. On the next page, look for What is Pre-Diabetes?

Gestational Diabetes

  • Your body develops this type of diabetes during pregnancy, most likely during the 24th to 28th week.
  • Treatment: You might not have any symptoms. If you are pregnant and at risk, you should be tested during your 24th to 28th week. If diagnosed, eat the right amount of healthy food, get regular physical activity, and check your blood sugar. Your baby will be closely monitored, too. Your baby may be harmed if the diabetes is not controlled.
  • Cause: Caused by the hormones of pregnancy or a shortage of insulin.
  • Risk: Happens in 2% to 5% of all pregnancies, but disappears when the pregnancy ends. Gestational diabetes occurs more in women who are overweight, have a family history of diabetes, and in African Americans, Hispanic Americans, and American Indians. Women who have had gestational diabetes in previous pregnancies have a 25-50% risk of developing Type 2 diabetes in the next 20 years after the baby is born.
  • Prevention: Nobody knows if gestational diabetes can be prevented.
  • Also called: Glucose intolerance of pregnancy or high blood glucose during pregnancy.
To learn more:
Managinging Gestational Diabetes: A Patient's Guide to a Healthy Pregnancy
(National Institute of Child Health & Human Development)
NICHHD provides the guide in PDF format. You may download it all at once or by sections. Adobe Acrobat Reader is linked to the site if you need to download it first. This guide answers questions about having gestational diabetes, how it affects the baby, what you can do to stay healthy, and what to expect after having the baby.
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Diabetes and Pregnancy
Links to sites which have been reviewed by librarians at the National Library of Medicine. Topics include General/Overviews, Clinical Trials, Diagnosis/Symptoms, Nutrition, Prevention/Screening, Research, Specific Conditions/Aspects, Organizations, Statistics, and more. Learn about gestational diabetes -- diabetes during pregnancy. Read about nutrition basics, screening for pregnant women, how to determine if you are at risk , infants of diabetic mothers, and taking charge of your diabetes during pregnancy. Select español from the menu bar for Spanish links.

Other Causes of Diabetes

There are some other causes of diabetes. They are much less common. High doses of medications, including steroids (the most common is prednisone) and niacin, can cause diabetes. The diabetes goes away when the medicine is stopped. Some diseases affecting the pancreas can also cause diabetes.

next » What are the signs and symptoms of diabetes?

Written by: Barbara Carlson, M.L.S.
Last Modified: Monday November 04, 2019 11:21 AM