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.

Study Overview
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Brief Summary
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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.

Official Title
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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.

Conditions
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Diabetes Mellitus, Type 2, Overweight and Obesity, PreDiabetes

Intervention / Treatment
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* Behavioral: Low-calorie and high-protein diet with the majority of protein coming from animal sources.
* Behavioral: Low-calorie and high-protein diet with the majority of protein coming from plant sources.


Participation Criteria
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Eligibility Criteria
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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.

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 80 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Single


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: High-protein animal diet.<br>Low-calorie and high-protein diet (35% of total calories), mostly of protein coming from animal sources (75% of total protein). | Behavioral: Low-calorie and high-protein diet with the majority of protein coming from animal sources.<br>* Diet was prescribed to the participant and menus and recipes were also provided.<br>|
| Experimental: High-protein vegetal diet.<br>Low-calorie and high-protein diet (35% of total calories), mostly of protein coming from plant sources (75% of total protein). | Behavioral: Low-calorie and high-protein diet with the majority of protein coming from plant sources.<br>* Diet was prescribed to the participant and menus and recipes were also provided.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Glucose change. | Glucose change assessed by difference in fasting glucose concentration (mg/dL and %) comparing 3 and 6 months visits with respect to baseline. | After 3 and 6 months of intervention. | 
| Glycated hemoglobin change. | Glycated hemoglobin change assessed by difference in glycated hemoglobin concentration (%) comparing 3 and 6 months visits with respect to baseline. | After 3 and 6 months of intervention. | 
| Insulin change. | Insulin change assessed by difference in fasting insulin concentration (UI/mL and %) comparing 3 and 6 months visits with respect to baseline. | After 3 and 6 months of intervention. | 
| HOMA-IR change. | 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. | After 3 and 6 months of intervention. | 
| Body fat mass change. | Body fat mass change assessed by difference in fat mass (%) comparing 3 and 6 months visits with respect to baseline. | After 3 and 6 months of intervention. | 
| Fat-free mass change. | Fat-free mass change assessed by difference in fat free-mass (%) comparing 3 and 6 months visits with respect to baseline. | After 3 and 6 months of intervention. | 
| Visceral fat mass change. | Visceral fat mass change assessed by difference in visceral fat mass (kg and %) comparing 3 and 6 months visits with respect to baseline. | After 3 and 6 months of intervention. | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Total cholesterol change. | Total cholesterol change assessed by difference in fasting total cholesterol concentration (mg/dL and %) comparing 3 and 6 months visits with respect to baseline. | After 3 and 6 months of intervention. | 
| LDL cholesterol change. | 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. | After 3 and 6 months of intervention. | 
| HDL cholesterol change. | HDL cholesterol change assessed by difference in fasting HDL cholesterol concentration (mg/dL and %) comparing 3 and 6 months visits with respect to baseline. | After 3 and 6 months of intervention. | 
| Triglycerides change. | Triglycerides change assessed by difference in fasting triglycerides concentration (mg/dL and %) comparing 3 and 6 months visits with respect to baseline. | After 3 and 6 months of intervention. |