Effect of protein ingestion on the glucose appearance rate in people with type 2 diabetes

Amino acids derived from ingested protein are potential substrates for gluc oneogenesis. However, several laboratories have reported that protein inges tion does not result in an increase in the circulating glucose concentratio n in people with or without type 2 diabetes. The reason for this has remain ed unclear. In people without diabetes it seems to be due to less glucose b eing produced and entering the circulation than the calculated theoretical amount. Therefore, we were interested in determining whether this also was the case in people with type 2 diabetes. Ten male subjects with untreated t ype 2 diabetes were given, in random sequence, 50 g protein in the form of very lean beef or only water at 0800 h and studied over the subsequent 8 h. Protein ingestion resulted in an increase in circulating insulin, C-peptide , glucagon, alpha amino and urea nitrogen, and triglycerides; a decrease in nonesterified fatty acids; and a modest increase in respiratory quotient. The total amount of protein deaminated and the amino groups incorporated in to urea was calculated to be similar to 20-23 g. The net amount of glucose estimated to be produced, based on the quantity of amino acids deaminated, was similar to 11-13 g. However, the amount of glucose appearing in the cir culation was only similar to2 g. The peripheral plasma glucose concentratio n decreased by similar to1 mM after ingestion of either protein or water, c onfirming that ingested protein does not result in a net increase in glucos e concentration, and results in only a modest increase in the rate of gluco se disappearance.