Human Faecal Microbiota in Type 2 Diabetes

Gut microbiota refers to the bacterial communities in the gastrointestinal tract. The diversity and quantity of bacteria vary depending on age of the individuals, daily diet and the segment of the intestine, which makes the gut microbiota one of the most complex bacterial ecosystems known to men. In general, over trillions of bacteria reside in human gut. Recent evidence indicates that gut microbiota could be involved in host metabolism by multiple pathways leading to the development of obesity and type 2 diabetes. Increased fat storage or obesity has become one of the leading public health issues in many developed and developing countries. However, it is not clear whether type 2 diabetes is associated with a unique gut microbiota profile. Therefore, the primary objective of the study is to compare the fecal microbiota of overweight type 2 diabetic subjects to that of age, gender and BMI matched subjects as well as with lean non-diabetic subjects. In addition, the investigators hypothesize that microbiota modifications with consumption of fiber rich food products can improve the metabolic outcomes of type 2 diabetics. To test this hypothesis, the investigators plan to provide each overweight participant with two cereal bars per day for 4 weeks. Anthropometric measurements and plasma parameters as well as the fecal microbiota will be determined.

Inclusion criteria

-All diabetic and control non-diabetic subjects (of same BMI) must comply with all the following inclusion criteria:

• Ethnic background: Caucasian
• BMI: 25 to 40 kg/m2
• Fasting blood glucose > 7 mmol/L
• Fasting Hemoglobin A1c > 7%
• Consume mainly typical Western diets daily
• Having obtained his/her informed consent

Lean non-diabetic healthy subjects must comply with the following inclusion criteria:

• Ethnic background: Caucasian
• BMI: 20 to 25 kg/m2
• Fasting blood glucose < 5.5 mmol/L
• Fasting Hemoglobin A1c < 6 %
• Consume mainly typical Western diets daily
• Having obtained his/her informed consent

Exclusion criteria

Diabetic and healthy (same BMI) subjects representing one or more of the following criteria are excluded from participation in the study.

• Dietary supplements or medications known to alter gut bacteria, such as antibiotic medication or intestinal transit modulators
• People actively take cortisol or dexamethasone should be excluded from the study
• People under a-amylase/a-glucosidase inhibitors should be excluded from the study. However, patients under metformin can be accepted for this study.
• Patients under metformin suffering from gastrointestinal side effects within a 6-month time period prior to the trial
• Regular consumption of fermented dairy products
• Vegetarians
• Frequent diarrhea (more than two loose stool per day) within 7 days before the enrollment
• HIV seropositive
• Having known gastrointestinal diseases such as ulcerative colitis, Crohn's disease, peptic ulcers and cancer
• Patients who cannot be expected to comply with treatment
• Currently participating or having participated in another clinical trial during the last 6 months prior to the beginning of this study
• Females with hormone therapy will be excluded from the study

Lean healthy subjects representing one or more of the following criteria are excluded from participation in the study.

• Dietary supplements or medications known to alter gut bacteria, such as antibiotic medication or intestinal transit modulators
• Regular consumption of fermented dairy products
• Vegetarians
• Frequent diarrhea (more than two loose stool per day) within 7 days before the enrollment
• HIV seropositive
• Having known gastrointestinal diseases such as ulcerative colitis, Crohn's disease, peptic ulcers and cancer
• Patients who cannot be expected to comply with treatment
• Currently participating or having participated in another clinical trial during the last 6 months prior to the beginning of this study
• Females with hormone therapy will be excluded from the study