Research

Hormonal

Metformin exerts glucose-lowering effects partly by altering gut microbiota composition to increase the production of short-chain fatty acids (propionate and butyrate) and modulate bile acid pools, which in turn stimulate incretin hormone release.

If you take metformin, part of its benefit comes from how it changes your gut bacteria to produce beneficial compounds like butyrate. Some people experience stomach upset or gas initially, which is a known side effect linked to these microbial changes. This discomfort often improves over time.

GoodSupportsHIGH confidence
Support for the causal effects of these GM differences in type 2 diabetes has been provided by randomised trials and studies in drug-naive individuals demonstrating that the GM compositional changes translate to enhanced production of propionate and butyrate [20, 21] and modulation of bile acid pools [21], which may mediate some of the glucose-lowering effects of metformin (Fig. 3) [20–22, 24].
Mariana X. Byndloss et al. · Diabetologia · 2024

Why this rating

Supported by randomized trials and drug-naive cohort studies, though the paper notes the need for more causal confirmation.

Source

The gut microbiota and diabetes: research, translation, and clinical applications – 2023 Diabetes, Diabetes Care, and Diabetologia Expert Forum

Mariana X. Byndloss et al. · Diabetologia · 2024

DOI 10.1007/s00125-024-06198-1

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DOI resolved against Crossref · corpus check 2026-06-10

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