Post-prandial protein handling is not impaired in type 2 diabetes patients when compared with normoglycemic controls

CONTEXT: The progressive loss of muscle mass with aging is accelerated in type 2 diabetes patients. It has been suggested that this is attributed to a blunted muscle protein synthetic response to food intake. OBJECTIVE: To test the hypothesis that the muscle protein synthetic response to protein ingestion is impaired in older type 2 diabetes patients when compared with healthy, normoglycemic controls. DESIGN: We conducted a parallel-group design, clinical intervention study between August 2011 and July 2012. SETTING: The study was conducted at our research unit of Maastricht University, the Netherlands. Intervention/ participants/ main outcome measures: Eleven older type 2 diabetes males (Diabetes; age: 71+/-1 y, BMI: 26.2+/-0.5 kg.m-2) and twelve age-, and BMI-matched normoglycemic controls (Control; age: 74+/-1 y, BMI: 24.8+/-1.1 kg.m-2) participated in an experiment in which they ingested 20 g intrinsically L-[1-13C]-phenylalanine labeled protein. Continuous intravenous L-[ring-2H5]-phenylalanine infusion was applied and blood and muscle samples were obtained to assess amino acid kinetics and muscle protein synthesis rates in the post-absorptive and post-prandial state. RESULTS: Plasma insulin concentrations increased following protein ingestion in both groups, with a greater rise in the Diabetes group. Post-absorptive and post-prandial muscle protein synthesis rates did not differ between groups and averaged 0.029+/-0.003 vs 0.029+/-0.003 %.h-1 and 0.031+/-0.002 vs 0.033+/-0.002 %.h-1 in the Diabetes and Control group, respectively. Post-prandial L-[1-13C]-phenylalanine incorporation in muscle protein did not differ between groups (0.018+/-0.001 vs 0.019+/-0.002 MPE, respectively). CONCLUSIONS: Post-absorptive muscle protein synthesis and post-prandial protein handling is not impaired in older individuals with type 2 diabetes when compared with age-matched, normoglycemic controls