Effect of Resistant Starch on Insulin Sensitivity and Beta Cell Function in Subjects With Prediabetes

To compare the use supplementation based on green banana flour versus placebo in the insulin sensitivity on individuals who have prediabetes.

In order to evaluate whether supplementation with green banana flour may improve insulin sensitivity of individuals with prediabetes, volunteers will be recruited by advertising on the web page of Hospital de Clinical de Porto Alegre. After screening and selection, they will be submitted to a clinical, laboratory and nutritional standard evaluation, assessment of physical activity and body fat composition.The laboratory evaluation will include the oral glucose tolerance test (OGGT 75g), lipid profile, insulin, C-peptide, glycated hemoglobin and glycated albumin. Insulin sensitivity and beta-cell function will be assessed by the hyperglycemic CLAMP before and after the intervention.Interim statistical analysis will be performed at the end of the participation of ten study volunteers.

Subjects will receive green banana flour or placebo for four weeks.

Eligibility Criteria:
Inclusion criteria

1. Serum glycated hemoglobin (A1c) values between 5.7 and 6.5%, or fasting glucose ≥ 5.55 mmol/L and \< 6.94 mmol/L or oral glucose tolerance test (75g) ≥7.77 and \<11.04 mmol /L.
2. Body mass index (BMI) ≥ 25 kg / m² (≥23 kg / m² for those of Asian origin) and ≤ 35 kg / m² for screening.
3. Stable weight (maximum variation of approximately 5%) for at least 4 weeks prior to screening.
4. Apt and willing to provide the written informed consent term and to comply with the requirements of the study protocol.

Exclusion Criteria:

1. Clinically symptomatic gastrointestinal disease including, but not limited to, inflammatory bowel disease.
2. History of gastric bypass, antrectomy, or resection of the small intestine.
3. History of chronic pancreatitis or acute idiopathic pancreatitis.
4. Myocardial infarction, coronary artery bypass grafting, post-transplant cardiomyopathy or stroke in the last 6 months.
5. Any anomaly in clinical laboratory tests which may prevent safe participation in the study.
6. Tumor diagnosed and / or treated (except basal cell skin cancer, cervical carcinoma in situ, or prostate cancer in situ) within the past 5 years.
7. Hemoglobinopathy or chronic anemia known.
8. Donation of one unit (500 ml) or more of blood, significant loss of blood equivalent to at least one unit of blood within the last 2 weeks or blood transfusion in the last 8 weeks.
9. Any concomitant medical condition / disorder which, in the investigator's opinion, is likely to:

   * Will interfere with the patient's ability to complete the entire study period or participate in all study activities;
   * Require, during the study, the administration of a treatment that may affect the interpretation of the efficacy and safety data.
10. Treatment with any oral antidiabetic medicinal product and / or herbal preparations / non-prescription medicines that may affect glycemic control within 12 weeks prior to screening.
11. Chronic treatment with oral or parenteral corticosteroids (\> 7 consecutive days of treatment) within 4 weeks prior to screening.
12. Treatment with weight-reducing agents (eg, orlistat, sibutramine, topiramate, bupropion) within the last 12 weeks prior to screening.
13. History of unstable hypertension (\> 170/105 mmHg) in the last 12 weeks prior to screening.
14. Treatment with a lipid-lowering drug that has not been kept in a stable dose within the last 8 weeks prior to screening.
15. Treatment with thyroid hormone that has not been kept in a stable dose in the last 12 weeks prior to screening.
16. Investigational drug use within 30 days or 5 half-lives (whichever is longer) prior to screening unless guidelines from local health authorities require a longer period.
17. Any of the following laboratory abnormalities in screening:

    * Alanine aminotransferase (ALT) and / or Aspartate aminotransferase (AST) 3 times the upper limit of normality;
    * Glomerular filtration estimated by the equation kidney disease ≤ 60 ml per min by 1.73 m².
    * Fasting triglycerides \> 5.6 mmol / L;
    * Thyroid stimulating hormone (TSH) outside normal range.
18. History of substance abuse (including alcohol) within the last year.
19. Women with potential to become pregnant and / or who are using local or systemic hormonal contraceptive method; Women in the follicular phase of the menstrual cycle and also pregnant and lactating women.
20. Potentially unreliable patients and those considered by the Investigator as unsuitable for the study.