Research synthesisModerate evidenceModerate effect6 studies · 4 beneficial · 2 neutral · 0 harmful
Across 6 studies, 4 reported beneficial effects of cinnamon on reducing hemoglobin A1c (HbA1c), with moderate effect sizes, while 2 found neutral results. The strongest evidence comes from a 2025 meta-analysis of 3,054 adults with type 2 diabetes, showing that doses ≤2 g/day reduced HbA1c (moderate effect, but with high heterogeneity). The median study duration among the 2 studies that reported it was 57 days (∼8 weeks), suggesting effects may require at least 8 weeks of supplementation. Most studies focused on clinical populations with type 2 diabetes.
- Effective dose range: ≤2 g/day
- Studied populations: adults with type 2 diabetes
Caveats: Some systematic reviews (e.g., 2023 network meta-analysis, 2024 meta-analysis) found cinnamon did not significantly reduce HbA1c compared to placebo, introducing inconsistency. The largest meta-analysis reported high heterogeneity (I²=92%), and one of the beneficial RCTs combined cinnamon with berberine, making it unclear whether cinnamon alone is responsible. Only 2 of 6 studies reported duration, limiting confidence in the time course of effects.
Generated Jul 15, 2026