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: The objective of the study was 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: A clinical intervention study with two parallel groups was conducted between August 2011 and July 2012.
Setting: The study was conducted at the research unit of Maastricht University, The Netherlands. Intervention, Participants, and Main Outcome Measures: Eleven older type 2 diabetes males [diabetes; age 71 ± 1 y, body mass index (BMI) 26.2 ± 0.5 kg/m(2)] and 12 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-(13)C]phenylalanine-labeled protein. Continuous iv L-[ring-(2)H5]phenylalanine infusion was applied, and blood and muscle samples were obtained to assess amino acid kinetics and muscle protein synthesis rates in the postabsorptive and postprandial state.
Results: Plasma insulin concentrations increased after protein ingestion in both groups, with a greater rise in the diabetes group. Postabsorptive and postprandial 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 versus control group, respectively. Postprandial L-[1-(13)C]phenylalanine incorporation into muscle protein did not differ between groups (0.018 ± 0.001 vs 0.019 ± 0.002 mole percent excess, respectively).
Conclusions: Postabsorptive muscle protein synthesis and postprandial protein handling is not impaired in older individuals with type 2 diabetes when compared with age-matched, normoglycemic controls.
Trial registration: ClinicalTrials.gov NCT01473576 NCT01576848.