An overnight 12 hour fasting blood sample was drawn by venipuncture. Glucose was measured by standard enzymatic procedures (coefficient of variation of 2.0%), A1c was assessed by high performance liquid chromatography (coefficient of variation of 2.58%), and serum insulin was determined by immunoassay (coefficient of variation 5.9–8.0%) (Ohio State University Medical Center, Columbus, OH). Participants were asked to record the type, dose and frequency of prescribed medications by means of an interview at the assessment visits to assess possible changes in glycemia due to medication changes.