Best Supplements for Reduced Fasting Blood Glucose Levels
Ranked by research evidence. Compare 78 supplements across 96 papers from the biomedical literature, with effect direction, evidence strength, and dose range for each.
Top picks by evidence
- High evidence4 studies
Across 4 studies, all reported beneficial effects of turmeric/curcumin on fasting blood glucose, with effect sizes ranging from small to moderate. A meta-analysis of 18 RCTs (2024) found a moderate mean reduction of -11.48 mg/dL (p < 0.01), while another meta-review (2025) reported a small mean difference of -6.30 mg/dL. The evidence primarily comes from clinical populations with type 2 diabetes or metabolic syndrome, and study durations were not consistently reported.
- Moderate evidence3 studies
Across 3 studies, all reported beneficial small-sized effects of L-carnitine supplementation on reducing fasting blood glucose levels. Studies included populations with PCOS, diabetes, and impaired glucose tolerance, with a median study duration of 42 days (based on one study).
- Moderate evidence3 studies
Across 3 meta-analyses, 2 out of 3 studies reported beneficial effects on fasting blood glucose, with effect sizes ranging from small to large. The most robust meta-analysis (2025, n=5026, evidence score 7) found a moderate beneficial effect with doses from 200 to 4600 mg/day. Evidence primarily comes from type 2 diabetes patients, and the median study duration across reported studies was only 7 days, which is short for assessing glycemic changes.
Dose: 200 to 4600 mg/day
- HighTurmericAcross 4 studies, all reported beneficial effects of turmeric/curcumin on fasting blood glucose, with effect sizes ranging from small to moderate. A meta-analysis of 18 RCTs (2024) found a moderate mean reduction of -11.48 mg/dL (p < 0.01), while another meta-review (2025) reported a small mean difference of -6.30 mg/dL. The evidence primarily comes from clinical populations with type 2 diabetes or metabolic syndrome, and study durations were not consistently reported.4 beneficial4 studies
- ModerateL-CarnitineAcross 3 studies, all reported beneficial small-sized effects of L-carnitine supplementation on reducing fasting blood glucose levels. Studies included populations with PCOS, diabetes, and impaired glucose tolerance, with a median study duration of 42 days (based on one study).3 beneficial3 studies
- ModerateBlack CuminAcross 3 meta-analyses, 2 out of 3 studies reported beneficial effects on fasting blood glucose, with effect sizes ranging from small to large. The most robust meta-analysis (2025, n=5026, evidence score 7) found a moderate beneficial effect with doses from 200 to 4600 mg/day. Evidence primarily comes from type 2 diabetes patients, and the median study duration across reported studies was only 7 days, which is short for assessing glycemic changes. · Dose: 200 to 4600 mg/day2 beneficial1 neutral3 studies
- LowVitamin DAcross 4 studies, 1 reported a beneficial small-sized effect of vitamin D supplementation on reducing fasting blood glucose (FBG), while 3 found neutral effects. The single beneficial study was a meta-analysis in patients with metabolic-associated fatty liver disease (MAFLD) reporting a small significant reduction in FBG (weighted mean difference: -0.21, 95% CI: -0.41 to -0.02). Overall, the predominant effect size is small, and effects were observed at a median duration of 84 days (12 weeks), though most studies did not report a specific dose form or range. No single dose form was used consistently across studies.1 beneficial3 neutral4 studies