This antidepressant herb improves blood sugar, a little
STUDY: Bahari H et al, Food Science & Nutrition 2026;14:e71748
STUDY TYPE: Systematic review and dose-response meta-analysis
FUNDING: Independent
Background
Curcumin (turmeric) is an antiinflammatory herb with good evidence in depression, and this analysis looks at its effects on blood sugar (glucose).
The Study
Thirty-four randomized controlled trials (39 treatment arms, up to 235 participants each) tested curcumin against placebo in adults with prediabetes or type 2 diabetes, with interventions ranging from 4 to 48 weeks and doses from 80 mg to 2,100 mg/day (by comparison, a typical dose for depression is 1,000 mg daily).
Curcumin reduced:
- Fasting blood glucose by 10 mg/dL
- HbA1c by 0.32% (a measure of average glucose over a month)
- Fasting insulin modestly
- Insulin resistance (HOMA-IR) by 0.46 points
- Glucose tolerance test results also improved
- Pancreatic veta-cell function (HOMA-B) didn’t change
Who benefits most:
- Type 2 diabetes
- Overweight or obese patients
- Doses of 1,000 mg/day or more worked better for some outcomes
Oddly, curcumin combined with piperine, a pepper that is often added to raise absorpion, showed no significant effect on insulin or HOMA-IR, which the authors couldn’t fully explain (likely has to do with idiosyncrasies in those trials).
Limitations: The studies varied, so heterogeneity was large (I² above 90% for most outcomes), and the overall certainty of evidence was low. Eight of the 34 trials had a high overall risk of bias.
Practice Implications
- The results are meaningful: A 0.32% drop in HbA1c is at the lower end of what metformin achieves in high-risk patients.
- Risks: Curcumin has a mixed track record with liver toxicity, with signals of a problem in case reports but improvement in liver health in some trials. It may also impair iron absorption, and has possible drug interactions, inhibiting CYP1A2, CYP2C9, CYP2C19, CYP2D6, and CYP3A4.
- Consider curcumin for depressed patients with prediabetes or diabetes, and aim for supplements whose integrity is confirmed by independent labs.
— Chris Aiken, MD
Director, Psych Partners
Editor in Chief, Carlat Psychiatry Report
