Blood samples were collected after an overnight fast at the different study point. The serum was separated and immediately stored at −80 °C until posterior analysis. Enzimatic methods were used for the measurement of the levels of cholesterol, triglycerides, high density lipoprotein cholesterol (HDL-cholesterol), and glucose (Randox Laboratories Ltd., Crumlin, UK). The Friedewald formula was used for the calculation of the levels of the low-density lipoprotein (LDL) cholesterol [25 (link)]. Glycosylated hemoglobin (HbA1c) was determined by Dimension Vista autoanalyzer (Siemens Healthcare Diagnostics, Munich, Germany).
The homeostasis model assessment of insulin resistance (HOMA-IR) index was calculated according to the formula: HOMA-IR = fasting plasma insulin (µU/mL) × fasting plasma glucose (mmol/L)/22.5.