New evidence
A 12-week trial added a specific Bifidobacterium strain to metformin and saw a statistically significant drop in HbA1c — but only in a small, early study on type 2 diabetes patients.
This is the first randomized trial to show that Bifidobacterium longum subsp. longum BL21 might help lower blood sugar control marker HbA1c in type 2 diabetes, but it's a single early result in a specific clinical population — so treat it as promising but far from proven.
In a 12-week trial, people with type 2 diabetes who took the probiotic BL21 alongside their usual metformin saw a significant drop in HbA1c (a key measure of average blood sugar over the prior 2-3 months) compared to those on placebo. While that effect was statistically significant, the same study found only non-significant trends for fasting blood sugar and insulin resistance, and changes in gut bacteria were reported as beneficial but without statistical testing — so the headline benefit is narrower than it might appear.
Where this fits in the evidence
This is among the first studies we've indexed on Bifidobacterium longum subsp. longum for Improved Glycemia — treat it as an early signal until more research accumulates.
The study
- Randomized Controlled Trial (RCT)
- 2026-01
- Food science & nutrition
- PubMed: 41523285
- DOI: 10.1002/fsn3.71437
- Full study breakdown →
This is a plain-language summary of a research finding, not medical advice. Pillser surfaces research signals to help you decide what's worth investigating — always consult a qualified professional before changing what you take.