Effect of a Low-calorie and High-protein Diet Specially Rich in Animal Protein Compared to a Low-calorie and High-protein Diet Specially Rich in Plant Protein on Glucose Metabolism in Subjects With Prediabetes or Type 2 Diabetes and Overweight or Obesity.

Effect of a Low-calorie and High-protein Diet Specially Rich in Animal Protein Compared to a Low-calorie and High-protein Diet Specially Rich in Plant Protein on Glucose Metabolism in Subjects With Prediabetes or Type 2 Diabetes and Overweight or Obesity.

A Randomized Study to Investigate the Effect of a Low-calorie and High-protein Diet Specially Rich in Animal Protein Compared to a Low-calorie and High-protein Diet Specially Rich in Plant Protein on Glucose Metabolism in Subjects With Prediabetes or Type 2 Diabetes and Overweight or Obesity.

The aim of the study is to explore the effect of a low-calorie diet rich in protein (with a content of 35% of the total calories of the diet), mostly coming from animal sources (75% of total protein), compared to a hypocaloric diet rich in protein (with a content of 35% of the total calories of the diet), mostly coming from plant sources (75% of total proteins), in subjects with prediabetes or type 2 diabetes and overweight or obesity, on body composition, glucose and lipid metabolisms, after 6 months of intervention. To achieve the objective, a nutritional intervention study is carried out by randomizing participants to: a) a hypocaloric and high-protein diet (35% of total calories), mostly of them coming from animal sources (75% of total protein); b) a hypocaloric and high-protein diet (35% of total calories), mostly of them coming from plant sources (75% of total protein). The study has a total duration of 6 months and include the assessment of clinical, anthropometric, biochemical and lifestyle parameters, at the beginning of the study and after 3 and 6 months of intervention.

Low-calorie and high-protein diet (35% of total calories), mostly of protein coming from animal sources (75% of total protein).

Low-calorie and high-protein diet (35% of total calories), mostly of protein coming from plant sources (75% of total protein).

Glucose change assessed by difference in fasting glucose concentration (mg/dL and %) comparing 3 and 6 months visits with respect to baseline.

Glycated hemoglobin change assessed by difference in glycated hemoglobin concentration (%) comparing 3 and 6 months visits with respect to baseline.

Insulin change assessed by difference in fasting insulin concentration (UI/mL and %) comparing 3 and 6 months visits with respect to baseline.

HOMA-IR change assessed by difference in HOMA-IR concentration (absolute units and %) comparing 3 and 6 months visits with respect to baseline. HOMA-IR is calculated by calculating: [(fasting glucose (mg/dL) x 0,0555) x fasting insulin (UI/ml)] ÷ 22,5.

Body fat mass change assessed by difference in fat mass (%) comparing 3 and 6 months visits with respect to baseline.

Fat-free mass change assessed by difference in fat free-mass (%) comparing 3 and 6 months visits with respect to baseline.

Visceral fat mass change assessed by difference in visceral fat mass (kg and %) comparing 3 and 6 months visits with respect to baseline.

Total cholesterol change assessed by difference in fasting total cholesterol concentration (mg/dL and %) comparing 3 and 6 months visits with respect to baseline.

Total LDL cholesterol change assessed by difference in fasting LDL cholesterol concentration (mg/dL and %) comparing 3 and 6 months visits with respect to baseline.

HDL cholesterol change assessed by difference in fasting HDL cholesterol concentration (mg/dL and %) comparing 3 and 6 months visits with respect to baseline.

Triglycerides change assessed by difference in fasting triglycerides concentration (mg/dL and %) comparing 3 and 6 months visits with respect to baseline.

C-reactive protein change assessed by difference in fasting C-reactive protein concentration (mg/dL and %) comparing 3 and 6 months visits with respect to baseline.

Liver enzymes (GGT, GOT and GPT) change assessed by difference in fasting liver enzymes concentration (U/L and %) comparing 3 and 6 months visits with respect to baseline.

Uric acid change assessed by difference in fasting uric acid concentration (mg/dL and %) comparing 3 and 6 months visits with respect to baseline.

GLP-1 change assessed by difference in fasting GLP-1 concentration (pg/mL and %) comparing 3 and 6 months visits with respect to baseline.

GIP change assessed by difference in fasting GIP concentration (pg/mL and %) comparing 3 and 6 months visits with respect to baseline.

IL-6 change assessed by difference in fasting IL-6 concentration (pg/mL and %) comparing 3 and 6 months visits with respect to baseline.

Leptin change assessed by difference in fasting leptin concentration (pg/mL and %) comparing 3 and 6 months visits with respect to baseline.

MCP1 change assessed by difference in fasting MCP1 concentration (pg/mL and %) comparing 3 and 6 months visits with respect to baseline.

TNF-alpha change assessed by difference in fasting TNF-alpha concentration (pg/mL and %) comparing 3 and 6 months visits with respect to baseline.

Inclusion Criteria: Aged between 18 and 80. BMI between 27.5 kg/m2 and 40 kg/m2. Diagnosed as prediabetes or type 2 diabetes according to ADA criteria. Informed consent to be signed. Exclusion Criteria: Taking antidiabetic drugs (except for metformin with stable dose in the previous 6 months). Taking lipid-lowering drugs in unstable dose in the previous 2 months. Taking functional foods (i.e. sterols enriched food) or any other dietary supplement with a significant effect on lipid and glucose metabolism and body weight. Uncontrolled type 2 diabetes (i.e. glycated hemoglobin over 8%) Any disease that could affect study results (i.e. uncontrolled hypothyroidism). Alcohol intake over 30 g/day. Pregnancy or breastfeeding. Any other condition that investigators consider that could interfere with study outcomes.

Instituto de Investigación Sanitaria Aragón, Hospital Universitario Miguel Servet, Universidad de Zaragoza