Research

Hormonal

Metformin treatment alters gut microbiota composition (increasing Escherichia coli, decreasing Intestinibacter bartlettii) to enhance the production of short-chain fatty acids (propionate and butyrate) and modulate bile acid pools, which mediates glucose-lowering effects.

If you take metformin, your gut bacteria are actively helping lower your blood sugar by producing beneficial fats (SCFAs) and signaling molecules. However, this same bacterial shift can cause stomach upset for about 30% of users. If you experience GI distress, it may be linked to this mechanism, and discussing management strategies with your provider is important.

GoodSupportsHIGH confidence
Support for the causal effects of these GM differences in type 2 diabetes has been provided by randomized 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. · Diabetes Care · 2024

Why this rating

Supported by randomized trials and studies in drug-naive individuals, though the paper notes the GM might also cause side effects.

Source

The Gut Microbiota and Diabetes: Research, Translation, and Clinical Applications—2023 <i>Diabetes</i>, <i>Diabetes Care</i>, and <i>Diabetologia</i> Expert Forum

Mariana X. Byndloss et al. · Diabetes Care · 2024

DOI 10.2337/dci24-0052

narrative_reviewCited 25×
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DOI resolved against Crossref · corpus check 2026-06-10

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