Summary: In a small pilot trial in prediabetic older adults, 12 weeks of curcumin lowered HbA1c while placebo stayed stable, with only marginal enrichment of some beneficial gut bacteria and no change in weight, lipids, or overall microbiome diversity.
PICO Summary
| Element | Detail |
|---|---|
| Population | 28 adults aged ≥60 with prediabetes or overweight/obesity (23 completed); USA. |
| Intervention | Curcumin 80 mg daily for 12 weeks (n=14 completers). |
| Comparison | Placebo (n=9 completers); double-blind. |
| Outcome | HbA1c fell significantly with curcumin while remaining stable on placebo. BMI, lipids, and body composition did not change. AST rose in the curcumin group. Gut microbiome alpha and beta diversity were unchanged, with only marginal enrichment of some beneficial taxa over time. |
Curcumin in prediabetic older adults
Pilot RCT · prediabetes · 12 weeks
In this underpowered pilot, curcumin produced a small within-group HbA1c fall while placebo held steady, but the group-by-time interaction was not significant and weight, lipids, and microbiome diversity were unchanged.
Expert Commentary
This is an honestly reported pilot, and it deserves to be read as the modest, exploratory study it is rather than the stronger result the headline implies. The one encouraging signal is glycaemic: HbA1c fell in the curcumin group while the placebo group held steady, which is at least consistent with a small insulin-sensitising effect. But the gut-health claim needs tempering, because the microbiome showed no change in overall diversity and only a marginal enrichment of a few beneficial organisms, which is a long way from demonstrating improved gut health. Several other things give me pause: with only twenty-three completers this is underpowered, weight and lipids did not move, and AST actually rose in the curcumin arm, a minor but worth-noting hepatic signal given how heavily curcumin is marketed as liver-friendly. Can I use this with my patients? Barely, and only with candour. For a prediabetic older adult curious about curcumin, I can say a small pilot hinted at a glycaemic benefit but proved nothing about weight, lipids, or gut health, and that the foundations, diet, activity, and weight management, are what actually prevent progression to diabetes. Larger, longer trials are needed.
References
Lamichhane G, Godsey TJ, Liu J, et al. Twelve-week curcumin supplementation improves glucose homeostasis and gut health in prediabetic older adults: a pilot, double-blind, placebo-controlled trial. Nutrients. 2025;17(13):2164. doi:10.3390/nu17132164