Nutraceutical Improvement of Glucose Metabolism, NAFLD and Insulin Resistance by Oat-fiber Supplementation in Type 2 Diabetes Mellitus Patients

Cohort studies show an association between increased intake of insoluble (cereal) fiber and decreased risk for cardiovascular disease, type 2 diabetes (T2DM), non-alcoholic fatty liver disease (NAFLD), cancer, infectious and inflammatory disorders. Intervention studies, specifically addressing non-fermentable carbohydrates instead of their food sources (whole grain, pulses, legumes) are still sparse. Whole grain trials reported beneficial effects, but cannot pinpoint these benefits on fiber, as minerals, vitamins, grain protein and food matrix contribute to the metabolic results. The antidiabetic effectiveness of cereal fiber might be explained by a) an increased secretion of incretins and other glucose-induced gastrointestinal hormones, b) an alteration of the gut microbiome, or c) a fermentation to short-chain fatty acids. Fermentable fibers (most of which are soluble) show these mechanisms, but lack strong diabetes-protective associations in cohort studies. In recent supplementation trials, insoluble, mostly non-fermentable fibers improved insulin resistance, glycemia and inflammation in patients with metabolic syndrome or prediabetes. Between 2022-2024, we want to assess the effectiveness of insoluble, poorly fermentable cereal fiber in a shorter Intervention period in patients with high responsiveness (insulin-naïve overt type 2 diabetes mellitus with insulin resistance and NAFLD), using an oat fiber drinking supplement. Our triple-blinded RCT compares the metabolic effects and mechanistic outcomes of isocaloric treatments with 15 grams of oat-fiber supplement per day (vs. placebo) in 92 patients, covering an intervention period of 12 weeks.