High-protein energy-restricted diets induce greater improvement in glucose homeostasis but not in adipokines comparing to standard-protein diets in early-onset diabetic adults with overweight or obesity
Victoria Marco-Benedí clin nutr. May 2020Volume 39, Issue 5, Pages 1354–1363
Background & aims
It has not been elucidated if an energy-restricted diet with high protein content could induce a benefit in insulin resistance in subjects with type 2 diabetes (T2DM); and if an adipose tissue functionality improvement could mediate this effect. We aimed to assess the effect of energy-restricted diets with standard (18% from total calories; SP) vs high (35%) protein (HP), mainly coming from lean animal source, composition on glucose metabolism and adipokine concentration in overweight and obese subjects with T2DM. HOMA-IR change was the primary outcome.
Methods
Six-month weight-loss intervention including 73 subjects (43.8% men, 55.6 ± 8.37 aged and 32.8 ± 3.67 of BMI) with T2DM that were randomized to follow one of two calorie-restricted diets with the following distribution of calories: 18% (0.75 [95%CI: 0.71–0.78] g/kg/day) protein, 52% carbohydrates and 30% fat, or 35% (1.34 [95%CI: 1.27–1.41] g/kg/day) protein, 35% carbohydrates, and 30% fat. Anthropometric, clinical, biochemical (involving leptin, RBP4 and adiponectin) and lifestyle assessments were performed.
Results
Sixty-seven participants completed the study. Weight loss homogenously decreased among diets. HOMA-IR in HP diminished 2-fold than in SP diet (P = 0.023 and P = 0.004 at 3 and 6-months between diets). Participants following HP diet showed higher decrease in insulin, in glucose at 6-months (P = 0.004) and in HbA1c at 3-months (P = 0.003). RBP4 and leptin significantly decreased in both diets although no differences were found between diets. Adiponectin increased by 6.05% and 29.9% at 3-months in SP and HP diets, respectively (P = 0.167), and 23.7% and 53.5% at 6-months in SP and HP diets (P = 0.219). Adiponectin variation was inversely correlated with HbA1c, insulin and HOMA-IR changes at 6-months.
Conclusions
An energy-restricted diet containing 35% of total calories coming from protein lead to a greater improvement in glucose homeostasis, indicated by HOMA-IR and fasting plasma insulin concentrations, irrespective of weight loss in subjects with prediabetes or early stages of T2DM. This effect cannot be explained by changes in plasma concentration of adipokines.