INCIDENCE OF NIDDM AND THE EFFECTS OF GENDER, OBESITY AND HYPERINSULINEMIA IN TAIWAN

Our aim is to determine non-insulin-dependent diabetes mellitus (NIDDM ) incidence in Taiwan and examine its relation to obesity and hyperins ulinaemia in Chinese men and women. A total of 995 men and 1195 women aged 35-74 years free from diabetes in two townships in Taiwan were fo llowed up with a second examination. At baseline general and metabolic data were recorded, and detailed anthropometric parameters and plasma glucose and insulin were assessed. World Health Organisation (WHO) cr iteria of fasting glucose 7.8 mmol/l or greater was utilized for defin ing diabetes. The age-standardized incidence rate based on the United States population in 1970 was 9.3/1000 (CI 5.8-12.8) in men and 9.3/10 00 (CI 6.2-12.4) in women and the based on the WHO population in 1976 was 8.9/1000 (CI .5-12.3) in men and 8.9/1000 (CI 5.9-11.9) in women f or the Chinese who had a mean BMI slightly greater than 24 (kg/m(2)). The predictability of the plasma glucose level was greater than that o f the insulin level and the obesity indices. NIDDM incidence increased approximately threefold with each 0.67 mmol/l increase in plasma gluc ose level in men and women. The present study demonstrated the essenti al relationship of not only BMI but also central obesity indices (such as subscapular and waist circumference) to the incidence of NIDDM amo ng men and women and a stronger relationship between NIDDM incidence a nd obesity in women than in men. The predictive effects of obesity ind ices and fasting plasma insulin values on NIDDM risk were independent of each other in men. Obesity and hyperinsulinaemia each without the p resence of the other can lead to an increased risk of NIDDM. In women the NIDDM incidence increased more than additively in those with both obesity and hyperinsulinaemia compared to those with single obesity or hyperinsulinaemia. A slightly higher incidence of NIDDM in Taiwan tha n in western countries was found. The importance of obesity is indicat ed for predicting NIDDM in the community. Hyperinsulinaemia was found to play a significant role in predicting NIDDM incidence independent o f obesity in men and synergistically with obesity in women.