No change of hyperleptinemia despite a decrease in insulin concentration in patients with chronic renal failure on a supplemented very low protein diet

Chronic renal failure (CRF) is often accompanied by hyperleptinemia caused by deficient renal metabolism of leptin and possibly increased leptin produ ction, which in turn may result from the hyperinsulinemia and increased pro inflammatory cytokine levels in patients with CRF. The hyperinsulinemia and insulin resistance observed in patients with CRF improve on supplemented v ery low protein diets (SVLPDs). The goal of our study is to determine wheth er the correction of hyperinsulinemia and insulin resistance in patients wi th CRF by SVLPDs is accompanied by improvement in hyperleptinemia. Thirteen patients were studied before and 1 year after following SVLPDs providing 0 .3 g/kg/d of protein, supplemented with amino acids and ketoanalogues. Afte r 1 year, patients showed markedly less hyperinsulinemia (7.4 +/- 1.6 versu s 13.8 +/- 2 muU/mL at the start of diet; P = 0.05) and insulin resistance, whereas serum leptin levels remained unchanged (16.1 +/- 4.7 versus 19.1 /- 7.4 ng/mL at start of the study; P = not significant). The initial corre lation between serum leptin level and percentage of body fat persisted duri ng follow-up. No correlation was found between insulin and leptin levels or between the variation of these two parameters during the study. Our study shows that the correction of hyperinsulinemia and insulin resistance in pat ients with CRF by SVLPDs is not accompanied by improvement in hyperleptinem ia, which consequently does not appear to result from changes in carbohydra te metabolism. (C) 2000 by the National Kidney Foundation, Inc.