Here's an overview of the most common types of diabetes:

Diabetes mellitus is defined as a fasting blood glucose of 126 milligrams per deciliter (mg/dL) or more. Prediabetes is a condition in which blood glucose levels are higher than normal (a fasting blood glucose level between 100 and 125 mg/dl) but not yet diabetic. Impaired fasting glucose (IFG) and impaired glucose tolerance (IGT) are intermediate states of abnormal glucose regulation between how a body normally uses glucose and diabetes.

• Impaired fasting glucose (100 to 125 mg/dL)
• Impaired glucose tolerance (fasting glucose less than 126 mg/dL and a glucose level between 140 and 199 mg/dL two hours after taking an oral glucose tolerance test)

Type 2 diabetes is the most common form of diabetes. It appears most often in middle-aged adults. Today, however, adolescents and young adults are developing type 2 diabetes at an alarming rate. It develops when your body doesn't make enough insulin or develops “insulin resistance” and can’t make efficient use of the insulin it makes.

Type 1 diabetes usually occurs in children and young adults. In type 1, the pancreas makes little or no insulin. Without daily injections of insulin, people with type 1 diabetes won't survive. 

Both type 1 and type 2 diabetes may be inherited in genes. A family history of diabetes can significantly increase the risk of developing diabetes. Untreated diabetes can lead to many serious medical problems. These include blindness, kidney disease, nerve disease, limb amputations and cardiovascular disease (CVD).

Treatment
Diabetes is treatable, but even when glucose levels are under control it greatly increases the risk of heart disease and stroke. In fact, most people with diabetes die of some form of heart or blood vessel disease.

Pre-diabetes and subsequent type 2 diabetes usually results from insulin resistance. When insulin resistance or diabetes occur with other CVD risk factors (such as obesity, high blood pressure, abnormal cholesterol and high triglycerides), the risk of heart disease and stroke rises even more.

When diabetes is detected, a doctor may prescribe changes in eating habits, weight control, exercise programs and medication to keep it in check. It's critical for people with diabetes to have regular check-ups.

Work closely with your healthcare provider to manage your diabetes and control any other risk factors. For example, blood pressure for people with diabetes should be lower than 130/80 mm Hg.

AHA Recommendation

Diabetes is a major risk factor for stroke and coronary heart disease, which includes heart attack. People with diabetes may avoid or delay heart and blood vessel disease by controlling the other risk factors.

It's especially important to control weight and blood cholesterol with a low-saturated-fat, low-cholesterol diet and regular physical activity. It's also important to lower high blood pressure and to not smoke.

This content is reviewed regularly. Last updated 10/13/08.