Best Supplements for Reduced Hemoglobin A1c
Ranked by research evidence. Compare 90 supplements across 137 papers from the biomedical literature, with effect direction, evidence strength, and dose range for each.
Top picks by evidence
- High evidence6 studies
Across 6 studies, 5 reported beneficial effects of black cumin (Nigella sativa) on reducing hemoglobin A1c (HbA1c), with predominantly moderate effect sizes. The most-studied populations include adults with type 2 diabetes (T2DM) or metabolic syndrome, with a wide dose range (200 to 4600 mg/day). Only 1 of 6 studies reported a duration (7 days), making conclusions about typical treatment length uncertain.
Dose: 200 to 4600 mg/day - Moderate evidence6 studies
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.
Dose: ≤2 g/day - Moderate evidence4 studies
All 4 studies reported beneficial effects of L-carnitine supplementation on reducing hemoglobin A1c, with effect sizes ranging from small to large. The most-studied dose range was 1-2 g/day, and effects were observed in adults with type 2 diabetes. One study with a median duration of 253 days suggests long-term supplementation may be needed for maximal effect, but duration data were limited.
Dose: 1-2 g/day
- HighBlack CuminAcross 6 studies, 5 reported beneficial effects of black cumin (Nigella sativa) on reducing hemoglobin A1c (HbA1c), with predominantly moderate effect sizes. The most-studied populations include adults with type 2 diabetes (T2DM) or metabolic syndrome, with a wide dose range (200 to 4600 mg/day). Only 1 of 6 studies reported a duration (7 days), making conclusions about typical treatment length uncertain. · Dose: 200 to 4600 mg/day5 beneficial1 neutral6 studies
- ModerateCinnamonAcross 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. · Dose: ≤2 g/day4 beneficial2 neutral6 studies
- ModerateL-CarnitineAll 4 studies reported beneficial effects of L-carnitine supplementation on reducing hemoglobin A1c, with effect sizes ranging from small to large. The most-studied dose range was 1-2 g/day, and effects were observed in adults with type 2 diabetes. One study with a median duration of 253 days suggests long-term supplementation may be needed for maximal effect, but duration data were limited. · Dose: 1-2 g/day4 beneficial4 studies
- ModerateAnthocyaninsAcross 4 studies, all reported beneficial effects, with moderate effect sizes most common. In type 2 diabetes populations, median doses of 320 mg/day were associated with reductions in HbA1c of approximately 0.3–0.5%. Effects were typically observed at 56 days or longer. · Dose: 320 mg/day (median)4 beneficial4 studies
- ModerateTurmericAcross 4 studies, 3 reported beneficial effects of turmeric on reducing hemoglobin A1c, with effect sizes ranging from small to moderate. The strongest evidence comes from a randomized controlled trial using 1500 mg/day for 365 days in adults with type 2 diabetes, which showed a small but statistically significant reduction in HbA1c (6.10% vs. 6.40%). Findings are consistent with meta-analytic data indicating a moderate reduction in HbA1c (e.g., MD = -0.31%), though one systematic review did not find turmeric significantly effective compared to other herbs. · Dose: 1500 mg/day3 beneficial1 neutral4 studies
- LowVitamin DAcross 7 studies, 2 reported beneficial moderate-sized effects on reducing Hemoglobin A1c, while 5 found neutral effects. The predominant effect size is moderate among beneficial studies, but the overall evidence is mixed, with most studies showing no significant impact. The median study duration was 98 days, and the most studied populations were clinical (e.g., type 2 diabetes patients).2 beneficial5 neutral7 studies
- ModerateTaurineAcross 3 studies (including two meta-analyses), 2 reported beneficial effects on reducing hemoglobin A1c, with effect sizes ranging from small to moderate; one randomized controlled trial protocol reported a neutral finding (not yet completed). The most-studied dose was 3 g/day, and the median study duration was 180 days. Evidence primarily comes from meta-analyses of clinical trials in populations with metabolic dysfunction or overweight/obesity. · Dose: 3 g/day2 beneficial1 neutral3 studies
- LowSaffronAcross 3 studies, 2 reported small beneficial effects of saffron supplementation on reducing hemoglobin A1c (HbA1c), while 1 found no significant effect. The two positive meta-analyses showed small reductions of approximately -0.22% to -0.25% in clinical populations with metabolic syndrome, type 2 diabetes, or related conditions. Doses ranged from 5 mg/day to 1 g/day, but no consistent dose range emerged.2 beneficial1 neutral3 studies
- Lowbrown riceAcross 3 studies, 1 reported a small beneficial effect on HbA1c in overweight adults with prediabetes or type 2 diabetes, while 2 found no significant effect. The predominant effect size is small, and effects were typically observed at study durations of 8-12 weeks. No specific dose or form was consistently reported.1 beneficial2 neutral3 studies
- LowGingerAcross 3 studies, 2 reported neutral small effects and 1 reported a beneficial moderate effect. The majority of studies do not show a statistically significant benefit of ginger for reducing HbA1c.1 beneficial2 neutral3 studies