Type 2 Diabetes

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While type 2 diabetes is not completely understood, recent research does suggest that certain lifestyle changes can prevent or delay the onset in adults who are at high risk of getting the disease. Modest weight loss (of 5 to 10 percent of body weight) and modest physical activity (30 minutes a day) are recommended goals.

This section contains information about prediabetes.


People with prediabetes have blood glucose levels that are higher than normal but not high enough that they qualify as having diabetes. This condition is diagnosed using one of two tests: the oral glucose tolerance test (OGGT), which entails fasting overnight, then having blood glucose levels measured before and two hours after drinking a glucose solution; and the fasting plasma glucose test, which requires one blood sample drawn after an overnight fast.

In people with prediabetes, the two-hour blood glucose level is between 140 and 199 mg/dl, and the fasting plasma glucose level is between 100 and 125 mg/dl. Those identified by the oral glucose tolerance test are said to have "impaired glucose tolerance (IGT)," and those identified by the fasting plasma glucose test are said to have "impaired fasting glucose (IFG)."

A reading of normal for the first test is no higher than 140 mg/dl at the two-hour mark. For the fasting plasma glucose test, normal is under 100 mg/dl. Diabetes is defined as a glucose tolerance level of 200 mg/dl or a fasting plasma glucose level of 126 mg/dl or greater on two separate occasions. Or, if diabetes symptoms exist and two blood draws taken at random show levels of 200 mg/dl or higher, diabetes is indicated.

Studies indicate that most people with prediabetes develop diabetes within 10 years. This risk rises as people become more overweight and more sedentary, and if they have a family history of diabetes.

A recent study found that people with glucose levels in the upper half of the impaired glucose tolerance range could lower their risk of developing diabetes by 58 percent by following a healthful diet and a moderate exercise program that enabled them to lose about 5 to 7 percent of their body weight. People taking the medication metformin reduced their risk by 31 percent. Though researchers studied the interventions only in people in the upper half of the danger zone, many researchers think it is reasonable to assume that millions more people would also benefit from cutting back on fats and portion sizes; emphasizing fruits, vegetables, and lean cuts of meat; and walking 30 minutes a day.

Last reviewed on 11/10/2008

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