RESEARCH DESIGN AND METHODS

The study design, protocol, and laboratory methods have been fully described previously (11). The study protocol was approved by the research ethics board at Mount Sinai Hospital, and all subjects gave written informed consent. In brief, participants consisted of 180 healthy pregnant women attending outpatient obstetrics clinics who had been referred for a 100-g oral glucose tolerance test (OGTT) following an abnormal result on a screening 50-g glucose challenge test (plasma glucose≥ 7.8 mmol/l at 1 h postchallenge). As previously described (11), the OGTT stratified participants into three glycemic tolerance groups, 1) GDM, 2) impaired glucose tolerance (IGT), and 3) normal glucose tolerance (NGT). Venous blood samples for laboratory measurement of adiponectin and fasting insulin were drawn during the OGTT. Plasma adiponectin concentration was measured at 180 min (adiponectin level is not affected by food intake [5]) by radioimmunoassay (Linco Research) with a coefficient of variation of 9.3%. Specific insulin was measured using the Roche Elecsys 1010 immunoassay analyzer and the electrochemiluminescence immunoassay kit. This assay shows 0.05% cross-reactivity to intact human proinsulin and the primary circulating split form (Des 31, 32). Demographic and historical information was collected by interviewer administered questionnaire.