OPTIFIT-Optimal Fiber Trial for Diabetes Prevention

Study Overview
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Brief Summary
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High intake of insoluble fiber is strongly associated with a reduced incidence of diabetes and cardiovascular events in prospective observation studies. Our primary objective is to compare a life style diabetes prevention program(PRAEDIAS) with and without added insoluble fibers in its effectiveness to prevent incident diabetes type 2 in high risk individuals with impaired glucose tolerance. Subjects with IGT not willing to participate in the intervention will be used as independent controls. Secondary aims are to identify mechanisms of action with regard to body composition, anti-inflammatory and metabolic effects of fibers. We propose a randomized, prospective intervention study. The results will be of general relevance for guidance of fiber intake in the population and will help the food industry to design healthy high fiber foods. Fiber can be added at low cost to numerous foods. Increased fiber intake may therefore provide a simple non-cognitive prevention strategy effective at the population level.

Detailed Description
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The overall objective is to investigate whether insoluble fibers added to standard nutrition can reduce the progression of impairment of glucose metabolism in a high risk population with impaired glucose metabolism. Large prospective cohort studies clearly show that mainly insoluble cereal fiber from whole grains is associated with reduced risk of type 2 diabetes and cardiovascular disease. However, there is a lack of evidence from prospective intervention studies targeted to evaluate the potential of dietary fibers to reduce diabetes and cardiovascular disease as recently stated by the Cochrane Foundation. Dietary fiber intake is generally much lower than currently recommended, which may in part be related to side effects of whole grain nutrients and their gustatory properties. Intestinally uncomfortable effects are at least partly related to fermentation which is much less induced by insoluble non-fermentable fibers than by soluble fermentable fibers. The prospective demonstration of beneficial effects of insoluble fibers in preventing diabetes type 2 will allow detailed nutritional recommendations. This may serve to support the consumption of metabolically beneficial constituents of fiber-rich diets and help to increase fiber intake by high fiber natural nutrients or everyday nutrients enriched in insoluble natural fibers.

Official Title
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Investigation of the Effect of Insoluble Dietary Fiber on Carbohydrate and Lipid Metabolism and the Prevention of Diabetes Mellitus Type 2 in Subjects With Impaired Glucose Tolerance

Conditions
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Diabetes, Nutrition Disorders, Obesity, Overweight, Metabolic Syndrome x, Body Weight, Glucose Metabolism Disorders, Metabolic Diseases

Intervention / Treatment
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* Dietary Supplement: Fiber
* Dietary Supplement: Placebo


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Impaired glucose tolerance Age>18years old both gender Exclusion Criteria: Diabetes type 1 and type 2 chronic or malignant disease Intake of metabolic influence drugs Food allergies, fiber intolerance

Ages Eligible for Study
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Minimum Age: 18 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: Prevention
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Triple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Drink enriched in fibers<br>7,5g enriched fiber drinks, BID | Dietary Supplement: Fiber<br>* 200ml drinks enriched with 7,5g of fiber (90% insoluble fiber, 10% soluble fiber), BID, over 24 months<br>|
| Experimental: Placebo drink<br>Placebo drink, BID | Dietary Supplement: Placebo<br>* 200ml Placebo, BID, over 24 months<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change of 2h-postprandial blood glucose from IGT to diabetes mellitus type 2 or normal glucose tolerance (NGT) | Change of the glucose metabolism (OGTT) | 0, 12, 24 months | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change of insulin sensitivity | Measurement by HOMA and OGIS from the OGTT | 0, 12, 24 months | 
| Change of insulin secretion | Measurement by the OGTT | 0, 12, 24 months | 
| Expression of inflammatory markers in blood | CRP, leukocytes, adipocytokines | 0, 6, 12, 18, 24 months | 
| Biometric data | Nutritional impact of blood pressure, anthropometry (body weight and body composition) | 0, 6, 12, 18, 24 months | 
| Assessment of cognitive performance |  | 0, 12, 24 months | 
| Development of indices for the prediction of fat mass | Change of fat fraction in liver, abdominal and in the total body fat measuring by MRI/H1-spectroscopy | 0, 12, 24 months | 
| Determination of gene expression in adipose tissue | Determination of inflammatory and other transcripts in sc adipose tissue in a fat biopsy. | 0, 12, 24 month | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Nutritional support, Diet therapy, Diabetes prevention, Insoluble fiber, Healthy life style, Weight loss