Impaired glucose tolerance and NIDDM: does a lifestyle intervention program have an effect?

To determine whether a 2-year lifestyle intervention program improves glucose tolerance and lipid levels in people with persistent impaired glucose tolerance (IGT) or non-insulin-dependent diabetes mellitus (NIDDM).

Screening for IGT and NIDDM was carried out in 1,752 people. Subjects with persistent IGT or NIDDM completed three 2-h oral glucose tolerance tests (OGTTs) before the start of the study and after 2 years. A single OGTT was carried out every 3 months. A 4-day food diary and a 7-day exercise diary were completed, and weight, blood pressure, glycated hemoglobin (HbA1), plasma lipids, and fasting and 2-h serum insulin were measured at baseline and every 3 months. Subjects were encouraged to make dietary changes and increase exercise.

Thirty-two subjects with persistent IGT and 20 subjects with NIDDM were recruited. Women reported significant decreases in total and saturated fat and an increase in carbohydrate, but few subjects reached the recommended intakes. Men achieved smaller dietary changes. There were significant decreases in body mass index, fasting and 2-h plasma glucose, HbA1, total cholesterol, low-density lipoprotein cholesterol, and triglyceride levels in both the IGT and NIDDM groups during the study.

Results suggest that a diet and exercise program can result in significant improvements in a range of clinical and metabolic variables in some people with IGT or NIDDM, although the absence of a control group precludes firm conclusions. Screening for IGT in those at high risk for developing NIDDM and offering those with persistent IGT a lifestyle intervention program could help reduce the progression of IGT to NIDDM.