Impact of Starch Digestibility on Glycemic Variability and Control, Cardiometabolic and Inflammatory Profiles, Microbiota and Intestinal Health in Subjects With Insulin Resistance

Impact of Starch Digestibility on Glycemic Variability and Control, Cardiometabolic and Inflammatory Profiles, Microbiota and Intestinal Health in Subjects With Insulin Resistance

To study the potential impact of a diet rich in both Slowly Digestible Starch (SDS) and Resistant Starch (RS), we propose a 2-month nutritional intervention study in which we will study the evolution of carbohydrate variability and metabolism and health-related parameters in 40 volunteers with insulin resistance. Regular sampling of blood, urine and faeces as well as continuous measurement of blood glucose levels will be performed to assess changes in blood glucose levels, insulin resistance, lipid metabolism, inflammation and the composition of the microbiota following the introduction of starch products rich in SDS and RS into the diet.

Inclusion Criteria:

• General criteria:

• Age between 18 and 75 years (bounds included)
• HOMA-IR ≥ 2.5
• Body Mass Index (BMI) between 25 and 40 kg/m² (bounds included)
• Stable weight over the past 3 months (+/- 5% of body weight)
• Waist circumference > 80 cm for women, > 94 cm for men
• Sedentary subject or subject practising regular and stable physical activity for the duration of the study (maximum 4 hours per week)
• Able to understand the provided information and having signed the informed consent forms
• Able to read and write in French
• Having a freezer and comfortable with storing stool samples at home
• Having undergone a prior medical examination during the screening visit

Food-related criteria:

• Willing to modify their diet for 2 months
• No food intolerances or allergies
• Regular consumption of the study products
• Fiber intake ≤ 25 g/day
• Willing to consume three main meals with no more than one snack per day and to take meals or snacks at least two hours apart

Exclusion Criteria:

• General criteria:

  • Adult under legal protection (guardianship or curatorship)
  • Person with unstable medical or psychological conditions that, according to the investigator, could lead to non-compliance or non-cooperation during the study or compromise safety or participation (as per Articles L.1121-6, L.1121-8, L.1121-9, and L.1122-1-2 of the French Public Health Code)
  • Presence of a condition identified during clinical examination or medical interview that could interfere with study evaluations, as judged by the investigator
  • Person deprived of liberty by judicial or administrative decision
  • Failure to comply with the exclusion period of another study as indicated in the "national volunteer database"
  • Person exceeding the annual compensation limit for participation in research protocols
  • Tobacco (or vaping equivalent) consumption > 5 cigarettes per day and inability to abstain from smoking or vaping from the evening prior to exploration days specified in the protocol
  • Alcoholism or alcohol abuse (> 30 g/day). Consuming more than three alcoholic drinks per day is considered abusive. One alcoholic drink corresponds to 30 mL of spirits, 120 mL of wine, or 330 mL of beer or abuse or dependency on another drug
  • Person not affiliated with a social security system or benefiting from a similar scheme
  • Absence of valid, approved health certificates in the event of government measures during an exceptional epidemic situation

• Biological criteria:

  • Fasting blood glucose ≥ 7 mmol/L or ≥ 1.26 g/L
  • Triglycerides > 4 g/L
  • LDL-cholesterol > 1.90 g/L
  • eGRF (estimated glomerular filtration rate) < 60 ml/min
  • Other biological abnormality with significant clinical relevance according to the investigator

• Population-related criteria :

  • Person with a specific dietary regimen (vegetarian, lacto-vegetarian, vegan, high-protein, low-carbohydrates, weight-loss diet, etc.)
  • Person consuming dietary supplements (prebiotics, probiotics, or minerals such as divalent cations like magnesium and calcium) regularly in the month before the selection visit and during the study
  • Blood donation within 2 months prior to the selection visit
  • Claustrophobia preventing indirect calorimetry measurement
  • Limited venous access making blood sampling and catheter placement difficult

• Therapeutic and medical criteria:

  • Type 1 or Type 2 diabetes
  • Systolic blood pressure ≥ 140 mmHg
  • Diastolic blood pressure ≥ 90 mmHg
  • Hypertension treatment
  • Known endocrine pathology interfering with carbohydrate metabolism (uncontrolled thyroid dysfunction, acromegaly, hypercortisolism, etc.)
  • Gastrointestinal diseases with an inflammatory component or associated with malabsorption or considered likely to interfere with the results of the study;
  • History of bloody diarrhea
  • Exocrine pancreatic insufficiency
  • History of bariatric surgery
  • History of digestive surgery, except appendectomy and simple hernia repair
  • Severe eating disorders (e.g., anorexia, bulimia, binge-eating disorder, night-eating syndrome) as judged by the investigator;
  • Hepatocellular insufficiency
  • Immunosuppressed individuals (e.g., those with AIDS, lymphoma, long-term corticosteroid therapy, chemotherapy, or allogeneic transplant)
  • Central venous catheter carriers and post-surgical patients
  • Any other clinically significant unstable or untreated abnormality in the immunological, neoplastic, endocrine, hematological, gastrointestinal, hepatic, neurological, or psychiatric domains, as judged by the investigator
  • Obesity medication use within the past 3 months or during the study
  • Antibiotic use in the month prior to explorations (for common beta-lactam antibiotics) or within 3 months before explorations (for other antibiotics), as judged by the investigator
  • Daily laxative use within the 3 months prior to explorations or other medications significantly interfering with gut microbiota composition;
  • Use of treatments that could interfere with study measurements, as judged by the study's co-investigating physicians
  • Pregnant, planning to become pregnant (verified by a blood pregnancy test), or breastfeeding woman
  • Person with known allergy to adhesive materials