Glucose and protein metabolic responses to an energy‐ but not protein‐ restricted diet in type 2 diabetes (original) (raw)

2020, Diabetes, Obesity and Metabolism

Aims: To test the effect of energy restriction with maintained protein intake on body composition and the insulin sensitivity of glucose and protein metabolism in adults with type 2 diabetes mellitus (T2D). Materials and methods: After 3d of an isoenergetic diet with 1.2 g/kg/d protein, obese T2D adults (3 women, 2 men) followed a 5-week diet providing 60% of energy requirements with 45% carbohydrate, and protein maintained at pre-intervention level. Isotopic tracers were used to quantify whole-body glucose (3-3 H-glucose) and protein (13 C-leucine) metabolism pre-(day 4) and post-intervention (day 39), postabsorptive and during a hyperinsulinemic, isoglycemic, isoaminoacidemic clamp. Body composition was measured by dual-energy x-ray absorptiometry. Results: Post energy restriction, the 6% weight loss was from total body (11%) and visceral fat losses (25%), but lean mass was preserved. Fasting glucose, serum insulin, HOMA-IR and C-peptide decreased significantly (29%, 38%, 54% and 38%, respectively) as did other cardiometabolic risk factors. Between clamp studies, postabsorptive protein turnover and oxidation rates decreased (12% and 32%), resulting in less negative net balance, consistent with protein conservation. The rates of glucose turnover decreased, and glucose metabolic clearance rate improved (24%). During the clamp, protein flux was lower (9%) and breakdown suppressed (12%), and net balance became less negative but not different. Though glucose turnover did not differ, metabolic clearance improved 47%. Conclusions: In obese adults with T2D, an energy-restricted diet with maintained protein intake of ~1.2 g/kg/d improved kinetics of protein metabolism (particularly postabsorptive), preserved lean body mass and increased glucose metabolic clearance rate.