EFFECTS OF DIET AND EXERCISE IN PREVENTING NIDDM IN PEOPLE WITH IMPAIRED GLUCOSE-TOLERANCE - THE DA QING IGT AND DIABETES STUDY

QBJECTIVE - Individuals with impaired glucose tolerance (IGT) have a h igh risk of developing NIDDM. The purpose of this study was to determi ne whether diet and exercise interventions in those with IGT may delay the development of NIDDM, i.e., reduce the incidence of NIDDM, and th ereby reduce the overall incidence of diabetic complications, such as cardiovascular, renal, and retinal disease, and the excess mortality a ttributable to these complications. RESEARCH DESIGN AND METHODS - In 1 986, 110,660 men and women from 33 health care clinics in the city of Da Qing, China, were screened for IGT and NIDDM. Of these individuals, 577 were classified (using World Health Organization criteria) as hav ing IGT. Subjects were randomized by clinic into a clinical trial, eit her to a control group or to one of three active treatment groups: die t only, exercise only, or diet plus exercise. Follow-up evaluation exa minations were conducted at 2-year intervals over a 6-year period to i dentify subjects who developed NIDDM. Cox's proportional hazard analys is was used to determine if the incidence of NIDDM varied by treatment assignment. RESULTS - The cumulative incidence of diabetes at 6 years was 67.7% (95% CI, 59.8-75.2) in the control group compared with 43.8 % (95% CI, 35.5-52.3) in the diet group, 41.1% (95% CI, 33.4-49.4) in the exercise group, and 46.0% (95% CI, 37.3-54.7) in the diet-plus-exe rcise group (P < 0.05). When analyzed by clinic, each of the active in tervention groups differed significantly from the control clinics (P < 0.05). The relative decrease in rate of development of diabetes in th e active treatment groups was similar when subjects were stratified as lean or overweight (BMI < or greater than or equal to 25 kg/m(2)). In a proportional hazards analysis adjusted for differences in baseline BMI and fasting glucose, the diet, exercise, and diet-plus-exercise in terventions were associated with 31% (P < 0.03), 46% (P < 0.0005), and 42% (P < 0.005) reductions in risk of developing diabetes, respective ly. CONCLUSIONS - Diet and/or exercise interventions led to a signific ant decrease in the incidence of diabetes over a B-year period among t hose with IGT.