Adiponectin is positively associated with insulin resistance in subjects with type 2 diabetic nephropathy and effects of angiotensin II type 1 receptor blocker losartan

Abstract

Background. Plasma adiponectin concentration is inversely associated with renal function. There is little literature on adiponectin levels and regulation by anti-hypertensive medication with an angiotensin II type 1 receptor blocker (ARB), especially in subjects with type 2 diabetes in different stages of chronic kidney disease (CKD).Methods. Eighty subjects with type 2 diabetic nephropathy were randomly divided into two groups: losarten group (n = 41) and amlodipine group (n = 39). Fasting blood was drawn to determine HbA1c, insulin and adiponectin levels. Insulin resistance was calculated using fasting glucose and insulin, expressed as HOMA-IR. For assessment of the relationship between adiponectin and other parameters, Pearson sample correlation coefficients were used. After stratification, ARB losartan (100 mg daily) was administered for a period of 6 months.Results. There is a positive association between adiponectin and proteinuria, fasting insulin levels and HOMA-IR in both CKD stage 1-2 and stage 3-4. Baseline adiponectin levels were not related to baseline estimated glomerular filtration rate (eGFR). At baseline, the adiponectin concentration was high in all observed subjects, and after 3 and 6 months of treatment with losartan, adiponectin levels decreased in the losartan group as compared with the amlodipine group (P < 0.01). Also fasting insulin and HOMA-IR decreased during the 6-month follow-up compared with the control group (P < 0.01).Conclusion. Our results demonstrate that serum adiponectin levels in type 2 diabetic nephropathy are strongly positively associated with fasting insulin levels and insulin resistance. Declines in fasting insulin and HOMA-IR by losartan are accompanied by decreased adiponectin levels, might offer potential protection in humans. The paradoxical phenomenon merits further ascertainment in future studies.