Determination of optimal protein contents for a protein restriction diet in type 2 diabetic patients with microalbuminuria

To establish the method by which the optimal dietary protein content for ty pe 2 diabetic patients with nephropathy could be determined, dietary protei n content was reduced in gradated steps and renal function was evaluated at the completion of each diet. Eight type 2 diabetic patients with microalbu minuria were examined in this study. Renal function, urinary albumin excret ion rate (AER) and urinary excretion rates of prostaglandins were evaluated at the completion of each of three consecutive one-week dietary periods wh ere the protein content was 1.2, 0.8 and 0.6 g . kg Body Weight (BW)(-1) da y(-1) on the first, second and third week, respectively. Filtration fractio n (PF), AER and urinary excretion rates of prostaglandin E2 and 6-keto-pros taglandin F1 alpha significantly decreased in response to reduced dietary p rotein content from 1.2 to 0.8 g . kg BW-1 . day(-1). No additional decreas es in FF, AER and urinary excretion rates of these two prostaglandins were obtained after the 0.6 g kg BW-1 . day(-1) low protein diet period. The met hod evaluating renal hemodynamics at the completion of several consecutive one-week dietary periods was confirmed to be useful to determine the optima l protein contents in type 2 diabetic patients with nephropathy. The result showed that the optimal protein content in type 2 diabetic patients with m icroalbuminuria was 0.8 g . kg BW-1 . day(-1) and protein restriction of le ss than 0.8 g . kg BW-1 . day(-1) was not necessary for patients with this stage of diabetic nephropathy. A part of reasons in which FF decreased afte r reduced protein content in diet may be due to decreased prostaglandins pr oduction in the kidneys. - optimal dietary protein content; type 2 diabetes mellitus; microalbuminuria; diabetic nephropathy; prostaglandin (C) 2001 T ohoku University Medical Press.