Standing height and weight were recorded, and BMI was calculated (weight [in kilograms] divided by the square of height [in meters]).
Arterial blood pressure and lipids were measured as previously described (11). Blood glucose levels were measured immediately with a Beckman Glucose Analyzer (Beckman Instruments, Fullerton, CA). Serum insulin concentrations were assayed by means of radioimmunoassay (RIA100; Pharmacia, Erlangen, Germany). Precision was 12% for low (3 μU/ml) and 5% for high (90 μU/ml) serum levels. The intra-assay coefficient of variation was 9% and the limit of detection was 3 μU/ml. Insulin sensitivity was assessed by the calculation of the homeostasis model assessment-R approach (glucose × insulin/22.5).