A microbiome-based clinical decision score (MFS) derived from baseline gut microbiota can identify individuals with prediabetes who are highly likely to benefit from dietary fiber supplementation, with a score ≥25 predicting a 99% probability of glycemic improvement and ≤17 predicting a 99% probability of no benefit.

People with a specific mix of gut bacteria can break down fiber into molecules that trigger the gut to release a hormone that tells the pancreas to release more insulin, which lowers blood sugar. People without this bacterial mix cannot make enough of these molecules, so their blood sugar does not improve even when they eat more fiber.