Xiao-Ren Pan

OBJECTIVE: Individuals with impaired glucose tolerance (IGT) have a high risk of developing NIDDM. The purpose of this study was to determine whether diet and exercise interventions in those with IGT may delay the development of NIDDM, i.e., reduce the incidence of NIDDM, and thereby reduce the overall incidence of diabetic complications, such as cardiovascular, renal, and retinal disease, and the excess mortality attributable to these complications. RESEARCH DESIGN AND METHODS: In 1986, 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 having IGT. Subjects were randomized by clinic into a clinical trial, either to a control group or to one of three active treatment groups: diet only, exercise only, or diet plus exercise. Follow-up evaluation examinations were conducted at 2-year intervals over a 6-year period to identify subjects who developed NIDDM. Cox's proportional hazard analysis 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-exercise group (P < 0.05). When analyzed by clinic, each of the active intervention groups differed significantly from the control clinics (P < 0.05). The relative decrease in rate of development of diabetes in the active treatment groups was similar when subjects were stratified as lean or overweight (BMI < or > or = 25 kg/m2). In a proportional hazards analysis adjusted for differences in baseline BMI and fasting glucose, the diet, exercise, and diet-plus-exercise interventions were associated with 31% (P < 0.03), 46% (P < 0.0005), and 42% (P < 0.005) reductions in risk of developing diabetes, respectively. CONCLUSIONS: Diet and/or exercise interventions led to a significant decrease in the incidence of diabetes over a 6-year period among those with IGT.

OBJECTIVE: To determine the prevalence of IGT and diabetes and identify the occurrence of CVD and its risk factors. RESEARCH DESIGN AND METHODS: This study was a population-based, cross-sectional study of 110,660 residents, 25-74 yr of age of DaQing, Hei Long Jiang Province, China. RESULTS: Using 1985 WHO criteria, 577 (5.5/1000) subjects with IGT and 630 (6.0/1000) with newly diagnosed diabetes were identified. In addition, 190 (1.7/1000) with previously known diabetes were identified. Hypertension, obesity, and abnormal albumin excretion were twice as frequent in those with IGT as in 279 men and 240 women of similar age and sex distribution who had normal OGTTs. Plasma cholesterol and TGs were higher, and HDL cholesterol was lower in subjects with IGT than in nondiabetic subjects. Those with IGT had a prevalence of electrocardiographically recognized CHD 9.5-fold greater than the normoglycemic subjects. Subjects with IGT had higher plasma insulin concentrations, but the 1-h insulin-glucose ratio after the 75-g glucose load was lower. In a forward stepwise multiple logistic regression analysis, IGT itself remained an independent factor associated with CHD after adjustment for age, sex, cigarette smoking, plasma cholesterol, BP, and obesity. CONCLUSIONS: Therefore, in China, IGT may occur with almost as high a frequency as diabetes and is accompanied by an increased frequency of CVD and its risk factors. Estimates from this study indicate that > 12.0% of all ECG-indicated CHD in the Da Qing population occurs in individuals with IGT and NIDDM. The IGT subjects identified in this survey form the cohort for a long-term follow-up and intervention study.