Evaluation of protein in dietary management of diabetes mellitus.

Establishing appropriate recommendations for protein intake in the management of diabetes requires examination of the role that dietary protein plays in overall health, in the control of diabetes, and in the risks to health posed by diabetes. Achieving metabolic control and delaying and/or preventing diabetic complications have previously been established as primary goals for the dietary management of diabetes. Although the primary function of dietary protein is for growth and tissue maintenance, dietary protein may play a role in the regulation of glucose metabolism and in the development of diabetic renal complications. Approximately half of protein intake is considered to be available as glucose. Dietary composition also affects secretion of insulin and counterregulatory hormones. One-third of individuals with insulin-dependent diabetes and one-fifth of those with non-insulin-dependent diabetes develop nephropathy within 15 yr after the diagnosis of diabetes. High protein intake and hyperglycemia can increase the glomerular filtration rate and the work load of the kidney. There is growing evidence from clinical studies that the progression of renal disease is delayed by early protein restriction. More studies are needed to assess early risk of diabetic nephropathy and to determine whether protein restriction alters the course of diabetic nephropathy. A dietary intake of between 12 and 20% protein provides flexibility in food selection but exceeds actual needs. The adult Recommended Dietary Allowance of 0.8 g/kg body wt should provide guidance for determining desired protein intake for individuals with diabetes.