Effects of a low-protein, low-phosphorus diet on metabolic insulin clearance in patients with chronic renal failure

The metabolic clearance rate (MCR) of insulin was studied in 17 nondiabetic patients with advanced chronic renal failure (creatinine 479 +/- 15 mumol/L, glomerular filtration rate 14.6 +/- 2.9 mL/min) before and after 3 mo of a low-protein, low-phosphorus diet (LPD) providing daily per kilogram 0.3 protein of vegetal origin and 3-5 mg inorganic phosphorus. The energy supply (146 kJ.kg-1 x d-1) was furnished mainly by carbohydrates. The diet was supplemented with a mixture of essential amino acids and keto-analogues. The MCR of insulin was determined by using the euglycemic clamp technique. Before the diet the MCR of insulin was low (450 +/- 127 mL.min-1 x m-2) but increased significantly at the third month (568.8 +/- 148 mL.min-1 x m-2), reaching values close to the MCR of control subjects (630 +/- 135 mL.min-1 x m-2). Identical results have been described during hemodialysis of anephric patients, leading us to hypothesize that an LPD reduces the production of dialyzable factors that interfere with peripheral insulin metabolism.