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.