All the measurements were made after a 10-h overnight fast. Waist circumference, hip circumference, and blood pressure were measured while participants were barefoot and wearing light clothes after defecation. Blood samples were collected before and 2 h after a fixed breakfast (~300 kcal) for measurement of hemoglobin A1c (HbA1c), fasting lipid profile, fasting and 2-h postprandial plasma glucose (2hPPG), insulin, and C-peptide. Fasting and postprandial plasma glucose levels, lipid concentrations for total cholesterol, triglycerides, and HDL-cholesterol (HDL-c) were measured using an automated enzymatic method (7600-020 Chemical Analyzer, Hitachi, Japan). HbA1c levels were determined by high-performance liquid chromatography (D-10 analyzer, Bio-Rad, Hercules, CA). Fasting and 2-h postprandial plasma insulin and C-peptide were measured by radioimmunoassay (Centaur XP immunoassay system, Siemens Healthcare Diagnostics, New York, NY).
Homoeostasis model assessment (HOMA) was used to estimate basal β-cell function (HOMA-B) and insulin resistance (HOMA-IR). HOMA-B was calculated as [20× fasting insulin (FINS)] / [fasting plasma glucose (FPG)—3.5]. HOMA-IR was calculated as FPG × FINS / 22.5 [14 (link)].
Homoeostasis model assessment (HOMA) was used to estimate basal β-cell function (HOMA-B) and insulin resistance (HOMA-IR). HOMA-B was calculated as [20× fasting insulin (FINS)] / [fasting plasma glucose (FPG)—3.5]. HOMA-IR was calculated as FPG × FINS / 22.5 [14 (link)].