High-fibre Diet Reduces Weight in Newly Diagnosed Type II Diabetes

Researchers enrolled participants aged 18-70 years with newly diagnosed type 2 diabetes and obesity, and participants were randomised to either a high-fibre dietary intervention or metformin monotherapy. 

The high-fibre group received two standardised fibre formulations and dietary guidance but no glucose-lowering medication. The metformin group received metformin according to routine clinical practice.  

Primary clinical outcomes were HbA1c and BMI and secondary clinical outcomes included fasting blood glucose, glycated serum protein and glucose responses during the meal tolerance test (MTT). 

Participants recorded types and amounts of foods consumed using a food frequency questionnaire and 24-h dietary recalls.  

High-Fiber Diet Outperforms Metformin 

High-fibre diet achieved significantly better glycemic control and weight-related outcomes than those receiving metformin alone and had a lower adjusted HbA1c at the end of the study and a lower adjusted BMI. 

Continuous glucose monitoring showed that high-fiber participants had significantly better glucose stability. Compared with the metformin group, participants in the high-fibre group had lower mean blood glucose levels, lower glucose coefficient of variation, and lower standard deviation of glucose. 

Participants in the high-fibre group had significantly lower waist-to-hip ratios, as well as lower leg fat mass, trunk fat mass, and total body fat mass. Serum triglyceride levels were also significantly lower than in the metformin group. 

Overall microbial community structure differed significantly from baseline and from that seen in the metformin group. Several bacterial species associated with carbohydrate fermentation increased during the high-fibre intervention. 

Researchers found that participants whose acetate levels increased experienced significantly greater reductions in HbA1c at Days 28 and 56 and had distinct baseline microbiome characteristics. 

Clinical Implications of High-fibre dietary intervention 

Researchers concluded that a high-fibre dietary intervention may offer a promising strategy for managing newly diagnosed diabesity, delivering greater improvements in blood sugar control and body weight than metformin alone. Future studies involving larger patient populations and longer follow-up periods could help clarify the durability of these benefits and their underlying microbiome-related mechanisms. 

Reference

Li Y et al. High-fiber diet altered gut microbiota, improved glycemic control, and reduced body weight in newly diagnosed type 2 diabetes and obesity. Front Cell Infect Microbiol.2026. DOI; 10.3389/fmicb.2026.1972983.