Metabolite-based dietary supplementation in human type 1 diabetes is associated with microbiota and immune modulation

Single-arm, pilot-feasibility trial in adults with long-standing type 1 diabetes (ages 18–45; both sexes). Baseline HbA1c ≤ 8.5%; mean diabetes duration 14 ± 12 years; 60% on multiple daily injections. Of 25 screened, 20 started; 2 withdrew; 18 completed the 6-week supplementation with follow-up to 12 weeks.

HAMSAB (acetylated and butyrylated high-amylose maize starch); dosing started at 10 g/day, increased every 48 hours by 10 g to reach 40 g/day; taken as 20 g in the morning and 20 g at night for 6 weeks.

HAMSAB safely increased stool and plasma SCFAs (acetate, propionate, butyrate) and altered gut microbiota composition and function, with a shift toward an immunoregulatory phenotype in PBMCs. HbA1c and basal insulin did not change overall, but higher SCFA levels correlated with better glycemic control and lower basal insulin; SCFAs remained elevated at 12 weeks post-treatment in many participants. Authors conclude that dietary SCFA delivery via HAMSAB can remodel microbiota and immune responses in adults with T1D and may improve glycemic control, but a placebo-controlled, longer trial is needed to establish causality and efficacy.

No placebo control; small sample size; short duration (6 weeks) with 12-week follow-up; results are associative and not causal; not randomized or blinded; some withdrawals; limited generalizability to broader T1D populations.