Higher intakes of total, cereal, and fruit fiber are associated with a lower risk of T2D and a more favorable metabolic profile, with the gut microbiome potentially contributing to the beneficial association of fruit fiber.
Higher total fiber intake was associated with lower type 2 diabetes risk.
Higher cereal fiber intake was associated with lower type 2 diabetes risk, showing the strongest association among fiber sources examined.
Higher fruit fiber intake was associated with lower type 2 diabetes risk.
Vegetable fiber intake was not associated with favorable plasma metabolic biomarker profiles, unlike total, cereal, and fruit fiber.
Higher intakes of total fiber, cereal fiber, and fruit fiber were associated with a metabolomic profile indicative of lower T2D risk.
Multiple gut microbial species were associated with higher fruit fiber intake and a metabolomic profile indicating lower T2D risk.
The study used an integrated analysis combining epidemiological data with multiomic (metabolomic and gut microbial) data to examine fiber and T2D associations.
This research suggests that eating more fiber — particularly from cereals (such as whole grains) and fruits — is linked to a meaningfully lower risk of developing type 2 diabetes. The study followed over 195,000 adults in the United States for up to 34 years and found that people who ate the most total fiber had about a 12% lower risk of type 2 diabetes compared to those who ate the least, while those eating the most cereal fiber had about a 23% lower risk and those eating the most fruit fiber had about an 18% lower risk. Notably, vegetable fiber did not show the same protective association with blood-based metabolic markers, though the overall findings reinforce the importance of dietary fiber sources in diabetes prevention. Beyond simply tracking who developed diabetes, the researchers also examined blood-based metabolic markers and the gut microbiome to understand potential biological mechanisms. People with higher cereal and fruit fiber intakes had more favorable profiles of blood sugar regulation, blood fats, and inflammation — all factors related to diabetes risk. For fruit fiber specifically, certain beneficial gut bacteria (including Faecalibacterium prausnitzii, Ruminococcus lactaris, and Gemmiger formicilis) and enzymes involved in producing butyric acid (a beneficial compound made by gut bacteria) were also linked to a lower diabetes risk profile, suggesting the gut microbiome may help explain why fruit fiber is protective. This research suggests that the type of food providing dietary fiber matters, not just the total amount consumed. Prioritizing fiber from whole grains and fruits may offer particular metabolic benefits related to diabetes prevention, possibly in part through their effects on gut bacteria. Because this was an observational study, it cannot prove causation, but the consistency of findings across a large population over many decades, combined with the supporting biological data, strengthens the case for a meaningful link between fiber-rich diets and reduced diabetes risk.
Wan Y, Alessa H, Guasch-Ferré M, Tobias D, Lee K, Manson J, et al.. (2026). Intake of Fiber From Different Food Sources and Type 2 Diabetes Risk: An Integrated Analysis of Epidemiological and Multiomic Data.. Diabetes care. https://doi.org/10.2337/dc25-2957