• 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 used as fuel.

People with diabetes have high blood glucose. This is because their pancreas does not make enough insulin or their muscle, fat, and liver cells do not respond to insulin normally, or both.

There are three major types of diabetes:

• Type 1 diabetes is usually diagnosed in childhood. The body makes little or no insulin, and daily injections of insulin are required to sustain life. Without proper daily management, medical emergencies can arise.
• Type 2 diabetes is far more common than type 1 and makes up 90% or more of all cases of diabetes. It usually occurs in adulthood. Here, the pancreas does not make enough insulin to keep blood glucose levels normal, often because the body does not respond well to the insulin. Many people with type 2 diabetes do not know they have it, although it is a serious condition. Type 2 diabetes is becoming more common due to the growing number of older Americans, increasing obesity, and failure to exercise.
• Gestational diabetes is high blood glucose that develops at any time during pregnancy in a person who does not have diabetes.

Diabetes affects about 17 million Americans. There are many risk factors for diabetes, including:

• A parent, brother, or sister with diabetes
• Obesity
• Age greater than 45 years
• Some ethnic groups (particularly African-Americans and Hispanic Americans)
• Gestational diabetes or delivering a baby weighing more than 9 pounds
• High blood pressure
• High blood levels of triglycerides (a type of fat molecule)
• High blood cholesterol level

The American Diabetes Association recommends that all adults be screened for diabetes at least every three years. A person at high risk should be screened more often.