Objectives: To investigate prospectively the incidence, certain predictors and outcomes of type 2 diabetes (DM), as well as to determine its prevalence cross-sectionally, in a representative sample of Turkish men and women. Methods: Prospective evaluation of 3401 male and female participants (aged 48.2±12 years). Follow-up constituted 19,050 person-years. Individuals with DM were diagnosed with criteria of the American Diabetes Association. Fatal and nonfatal coronary heart disease (CHD) was identified by clinical findings and Minnesota coding of resting electrocardiograms. Cut-points of ≥95 cm in males and ≥91 cm in females were selected for abdominal obesity. For prospective evaluations, cases with DM or CHD were excluded. Results: Prevalence of DM in Turkish adults was estimated as 2.89 million (11.0% of the population aged ≥35 years). Over a mean follow-up of 5.9 years, incident DM developed in 223 subjects, yielding an incidence per 1000 person-years of 11.0 in women and 12.4 in men. This corresponded to a 300,000 annual incidence. Following risk parameter levels but not HDL-cholesterol were significantly elevated at baseline in subjects developing DM compared to those without: age (5 years), waist girth (7 cm), blood pressure (12/6 mmHg), apolipoprotein B (7 mg/dl), total cholesterol (14 mg/dl), and fasting triglycerides (only in women, 52 mg/dl). Abdominal obesity (RR 2.61 [95%CI 1.87; 3.63]) and age in both genders, hypertension (RR 1.81 [95%CI 1.10; 2.98]) and low HDL-cholesterol in men alone were significant independent predictors of DM. Diabetes mellitus was a significant and independent predictor of fatal and nonfatal CHD, with a RR of 1.81 (95%CI 1.19; 2.75), after adjustment for sex, age, hypertension, waist circumference, serum total cholesterol and smoking status. Conclusions: The annual incidence of DM in Turkey rises very rapidly, currently stands at 300,000, and, hence, its prevalence also rises correspondingly. Insulin resistance appears to be a weak determinant of DM in Turkish women while abdominal obesity is the main determinant. Multivariately adjusted DM is a significant independent predictor of fatal and nonfatal CHD. These observations emphasize that measures to reverse or stop the "epidemic" of abdominal obesity are severely required.