The Interaction Between Protein Intake, Gut Microbiota and Type 2 Diabetes in Subjects With Different Ethnic Backgrounds
Condition: Type 2 Diabetes
MeSH terms: Diabetes Mellitus; Diabetes Mellitus, Type 2
Study type: Interventional

Summary: 
      Context and justification:

      There is growing evidence that the gut microbiota is a key element in the pathophysiology of
      cardio-metabolic diseases (CMD) such as Type 2 Diabetes (T2D). One hypothesis is that
      gut-derived metabolites (from diet) have an important role in the host metabolism.
      Preliminary results show that imidazole propionate (ImP), a degradation product of the
      essential amino acid histidine, is produced by the gut microbiota of T2D patients, but not
      healthy subjects. The gut microbiota itself is strongly influenced by diet and ethnicity.
      However, most dietary intervention studies have focused on the role of fiber intake and the
      effect of dietary protein on the gut microbiota composition and metabolite production is not
      well known. Our hypothesis is that, depending on the baseline gut microbiome composition, a
      diminution in protein intake could decrease the microbial production of metabolites such as
      ImP and improve the metabolism of the host. We also hypothesize that the effects of such an
      intervention could depend the ethnic background.

      Objective:

      To study the effects of a high protein (HP) vs a low protein (LP) diet on gut microbiota
      composition and production of pro-diabetic metabolites in type 2 diabetes (T2D) patients from
      Caucasian and Caribbean ethnicity depending on baseline metagenomics richness.

      Study design:

      Randomized controlled three months dietary intervention study

      Study Population:

      T2D patients from Caucasian (N=80) and Caribbean (N=40) background who are on a stable dose
      of metformin and do not use insulin or proton-pump inhibitors.

      Intervention:

      Subjects will be randomized to either a high protein (HP) or low protein (LP) diet for three
      months. Individuals of Caucasian ethnicity, will also be stratified according to either a
      high or low gut microbiota gene richness. All subjects will receive pre-cooked meals 6 days
      per week and daily food packages. Subjects are required to keep food diaries three days a
      week and will also have weekly contact with an Pitié-Salpêtrière dietician.

      Outcome measures:

      Primary endpoint is the change in glycemic excursion (area under the curve) after a mixed
      meal test between baseline and 12 weeks after the beginning of the intervention. Furthermore,
      we will study oral and fecal microbiota composition changes as well as serum levels of
      intestinal metabolites, such as ImP, body weight and body composition at baseline and after
      12 weeks.

      Sample Size:

      It is calculated that a total of 20 patients per arm are needed so 120 patients in total.
    

Detailed description: 
      Context and justification:

      There is growing evidence that the gut microbiota is a key element in the pathophysiology of
      cardio-metabolic diseases (CMD) such as Type 2 Diabetes (T2D). One hypothesis is that
      gut-derived metabolites (from diet) have an important role in the host metabolism.
      Preliminary results show that imidazole propionate (ImP), a degradation product of the
      essential amino acid histidine, is produced by the gut microbiota of T2D patients, but not
      healthy subjects. The gut microbiota itself is strongly influenced by diet and ethnicity.
      However, most dietary intervention studies have focused on the role of fiber intake and the
      effect of dietary protein on the gut microbiota composition and metabolite production is not
      well known. Moreover, it has been shown that the response to a dietary intervention may
      depend on the baseline gut microbiome richness.

      Main hypothesis: Depending on the baseline gut microbiome composition, a diminution in
      protein intake could decrease the microbial production of metabolites such as ImP and improve
      the metabolism of the host. We also hypothesize that the effects of such an intervention
      could depend the ethnic background.

      Study population:

      Individuals with type 2 diabetes (T2D), of Caucasian or Caribbean origin, 120 patients will
      be included in total

      Intervention:

      Assignment after randomization to one of the following 2 diets:

        -  HP diet: high protein (High Protein, HP) diet with 30% protein, 40% carbohydrate and 30%
           fat (as% of total energy intake)

        -  LP diet: low protein diet (Low Protein, LP) with 10% protein, 55% carbohydrate and 35%
           fat (as% of total energy intake) Food boxes adapted to each diet (HP or LP pre-cooked
           meals, HP or LP breads and snacks) will be provided to the participants throughout the
           study reaching 40-50% of their prescribed daily energy intake for 6 days per week.

      Subjects are required to keep food diaries three days a week and will also have weekly
      contact with a dietician.

      Visits:

      - Inclusion visit V0 (maximum 1 month before V1): Participants will first be recruited from
      the diabetic population of the French cohort of the European project METACARDIS. Individuals
      eligible for the study are screened for inclusion.

      Baseline phenotyping is performed (metabolic, inflammatory blood markers, stool and oral
      microbiota sampling, body composition by DXA, questionnaires)

      - Randomization visit V1 (T0 - start of the intervention): Randomization into 2 parallel
      groups (High Protein or Low protein diet) will be stratified based on metagenomics richness
      (obtained from Metacardis results), age (< or ≥ 60), gender, ethnic background (Caribbean or
      Caucasian).

      Meal tolerance test, anthropometric measures, resting energy expenditure measure, one week
      CGMS, 24h urinary urea measure are performed.

      - Follow-up visit V2 (T42 +/- 7 days): Mid protocol visit with anthropometric measures, one
      week CGMS, 24h urinary urea measures, stool sampling.

      - End of study visit V3 (T84 +/- 7 days): Phenotyping is performed (metabolic, inflammatory
      blood markers, stool and oral microbiota sampling, body composition by DXA, questionnaires,
      meal tolerance test, anthropometric measures, resting energy expenditure measure, one week
      CGMS, 24h urinary urea measure)

      Statistical analysis:

      There are no multiple hypotheses since our study has only one primary objective (AUC delta of
      the glycemic excursion after a mixed meal tolerance test (MMT) between the beginning of study
      and 3 months post intervention). Thus, the problem of the type 1 error will not arise.

      The primary endpoint will be analyzed to compare changes in AUC for glycemic excursion versus
      diet (rich vs. low protein), based on initial metagenomic richness (high vs. low) and
      ethnicity (Caucasian vs. Caribbean). AUC changes after dietary intervention between the
      different groups will be tested using linear regression models for repeated measurements with
      adjustment for initial levels. The effect of diet composition within the groups will be
      tested using Bonferroni's post-hoc covariance analysis (ANCOVA) analyzes. For secondary
      endpoints, the same approaches will be used for analysis of postprandial metabolites (AUC,
      AUC, post-MMT variation). Differences in relative abundance of bacterial species and
      functional modules (generated by metagenomic sequencing) and quality of life questionnaires
      will also be analyzed by subgroups using uni / multivariate analyzes. Correlations will be
      sought between changes in bio-clinical variables and changes in measurements of different
      metabolites.

      Funding:

        -  European Program (Join Program Initiative, JPI HDHL / ERA-NET cofund HDHL-INTIMIC,
           -Edition 2017) through the National Agency for Research (ANR)

        -  Leducq Foundation (Research Grant 17CVD01 titled "Gut Microbiome as a Target for the
           Treatment of Cardiometabolic Diseases").

        -  K Santé Society providing meals for the study.

        -  Nutrisens Society providing snacks for the study.
    

Intervention name(s): Diet HP; Diet LP
Intervention type(s): Other; Other
Intervention description(s): 2000kcal for men 1800 kcal for women. Food boxes (HP pre-cooked meals and meat/chicken/fish portions, HP breads and snacks) will be provided to the participants throughout the study reaching 40-50% of their prescribed daily energy intake for 6 days per week. In total 932 kcal are provided through this food boxes (54g of carbohydrate, 101g of protein, 34,6g of fat). The rest of the daily food intake will be guided by a dietician with a list of recommended high protein foods.
Subjects are required to keep food diaries three days a week and will also have weekly contact with a dietician.; 2000kcal for men 1800 kcal for women. Food boxes (LP pre-cooked meals, LP breads and snacks) will be provided to the participants throughout the study
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: None (Open Label)
Primary purpose: Treatment
Keywords: Type 2 diabetes; Diet; Protein; Gut microbiota; Metabolites