To examine the association of body mass index (BMI), waist-hip ratio (WHR), and waist circumference (WC) with fasting hyperglycemia after adjustment for age, cigarette smoking, and alcohol use. A cross-sectional survey was conducted among individuals visiting four health-screening centers across Taiwan. A total of 61 568 subjects (28 734 men and 32 834 women) between 25 and 64 years of age were included. Fasting hyperglycemia was defined as fasting plasma glucose > or =6.1 mmol/l or current diagnosis and use of insulin or hypoglycemic agent. Fasting hyperglycemia was found in 11.0% of men and 8.3% of women. The factors significantly associated with fasting hyperglycemia in men were age, BMI, WHR, and heavy drinking, while for women these factors were age, educational level, BMI, WHR, and heavy smoking. For men, increased risk of fasting hyperglycemia started from age 30 to 34 years, BMI > or =25 kg/m2, and WHR > or =0.82. For women, increased risk of fasting hyperglycemia started from age 35 to 39 years, BMI > or =24 kg/m2, and WHR > or =0.74. WC lost its significance as a predictor of fasting hyperglycemia when WHR included in the model. This study found that central obesity and general obesity were both independently associated with increased risk of fasting hyperglycemia in Taiwanese. The relationship between fasting hyperglycemia and central fat accumulation (WHR) begins to appear at levels that would not be regarded as representing obesity in Western populations, suggesting the need to redefine cutoffs for central obesity in this population.