HbA1C is determined by high performance liquid chromatography on an Adams™ A1c HA-8160 8180 , Arkray - Menarini instrument (Zaventem, Belgium; reference range: 4.8-6.0%). A mean of four annual determinations of A1C is used to assess overall metabolic control over the past two years. Plasma Serum levels of creatinin, total cholesterol, HDL cholesterol and triglycerides are measured on a Vitros 750 XRC (Ortho Clinical Diagnostic, Johnson & Johnson, Buckinghamshire, UK) Dimension Vista 1500 System (Siemens Healthcare Diagnostics, Huizingen, Belgium) with reagents from the same manufacturer (REF K1270A for creatinin, REF K1027 for total cholesterol, REF K3048A for HDL-cholesterol, REF K2069 for triglycerides). HDL-C is measured on a Hitachi 912 (Roche Diagnostics, Mannheim, Germany). Serum creatinine is measured by an enzymatic method on a Vitros 750 (Ortho Clinical Diagnostic, Beerse, Belgium). The glomerular filtration rate (eGFR) is estimated using the abbreviated MDRD formula, including a correction factor of 0.742 for women. Plasma HMW adiponectin concentrations are measured by an enzyme-linked immunosorbent assay (ELISA) (EZHMWA-64K, Millipore, analytical sensitivity 0.5 ng/ml, intra-assay coefficient of variation [CV] 7.47%). Leptin is measured using an ELISA kit (HU Leptin kit, KAC2281, Life Technologies, sensitivity 3.5 pg/ml, intra-assay CV 5.75%). TNF-α is assayed using ELISA (HU TNF alpha kit, KHC3011, Life Technologies, sensitivity 1.7 pg/ml, intra-assay CV 6.38%) and IL-6 concentrations are measured using ELISA (HU IL-6 Chemiluminescence Elisa kit, KHC0069, Life Technologies, sensitivity 0.25 pg/ml, intra-assay CV 5.37%).