Glucose and protein metabolic responses to an energy- but not protein- restricted diet in type 2 diabetes.
AIMS
To test the effect of energy restriction with maintained protein intake on body composition and on insulin sensitivity of glucose and protein metabolism in adults with type 2 diabetes (T2D).


MATERIALS AND METHODS
After 3 days of an isoenergetic diet with 1.2 g/kg/d protein, obese adults with T2D (three women, two men) followed a 5-week diet providing 60% of energy requirements with 45% carbohydrate, and with 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), in the postabsorptive state and during a hyperinsulinaemic, isoglycaemic, isoaminoacidaemic clamp. Body composition was measured using dual-energy x-ray absorptiometry.


RESULTS
After energy restriction, 6% weight loss occurred via total body (11%) and visceral fat losses (25%), but lean mass was preserved. Fasting glucose level, serum insulin level, homeostatic model assessment of insulin resistance index and C-peptide level 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. Although glucose turnover did not differ, metabolic clearance improved by 47%.


CONCLUSIONS
In obese adults with T2D, an energy-restricted diet with maintained protein intake of ~1.2 g/kg/d improved the kinetics of protein metabolism (particularly in the postabsorptive state), and preserved lean body mass and increased glucose metabolic clearance rate.
['Coussa|Ayla|A|', 'Bassil|Maya|M|', 'Gougeon|Réjeanne|R|', 'Marliss|Errol B|EB|', 'Morais|José A|JA|0000-0001-9366-6626']
D000328:Adult D001786:Blood Glucose D001823:Body Composition D003924:Diabetes Mellitus, Type 2 D004734:Energy Metabolism D005260:Female D005947:Glucose D006801:Humans D007328:Insulin D008297:Male D009765:Obesity
protein metabolism type 2 diabetes obesity weight loss glucose metabolism