Serum adiponectin and progression of diabetic nephropathy in patients with type 1 diabetes

OBJECTIVE - The purpose of this study was to elucidate whether serum adiponectin is associated with progression of diabetic nephropathy in type 1 diabetic patients. RESEARCH DESIGN AND METHODS - This was a prospective follow-up study as a part of the nationwide Finnish Diabetic Nephropathy Study; 1,330 type 1 diabetic patients were followed for 5.0 +/- 2.2 years. Patients were divided at baseline into three groups according to their urinary albumin excretion rate (AER) in three consecutive overnight or 24-h urine collections: 818 patients with normoalbuminuria (AER <20 mu g/min), 216 patients with microalbuminuria (20 mu g/min <= AER < 200 mu g/min), and 296 patients with macroalbuminuria (AER >= 200 mu g/min). Progression of albuminuria was the main outcome. Adiponectin was measured by a time-resolved immunofluorometric assay, and the values were log-transformed and adjusted for age, BMI, and sex before analysis. RESULTS - Progression either to the next albuminuria level or to end-stage renal disease (ESRD) occurred in 193 patients. No difference in adiponectin concentrations was observed between progressors and nonprogressors in patients with normoalbuminuria or microalbuminuria. In the patients with macroalbuminuria, progression to ESRD was associated with higher adiponectin in the entire group (23.4 +/- 17.1 vs. 16.0 +/- 8.5 mg/l, P < 0.001) and in men (P < 0.001) and women (P < 0.001) separately. Progression to ESRD was also associated with systolic blood pressure, insulin dose, A1C, serum cholesterol, serum triglycerides, AER, and estimated glomerular filtration rate (eGFR). When these covariates were inserted in a Cox regression analysis; A1C, triglycerides, eGFR, and adiponectin were significantly associated with progression from macroalbuminuria. CONCLUSIONS - Increased serum adiponectin levels predict the progression from macroalbuminuria to ESRD in type 1 diabetic patients.