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Evidence-Based Supplement Research
Evidence-Based Supplement Research

L-Carnitine and Improved Fasting Plasma Glucose

Research synthesisLow evidenceMixed effect size4 studies · 2 beneficial · 2 neutral · 0 harmful

Across 4 studies, 2 reported beneficial moderate-sized effects on fasting plasma glucose, while 2 reported neutral small-sized effects, indicating mixed evidence. The most studied dose was 1 g/day, and effects were observed in clinical populations (type 2 diabetes and PCOS) over a median study duration of 169 days.

  • Effective dose range: 1 g/day
  • Studied populations: adults with type 2 diabetes, women with polycystic ovary syndrome (PCOS)

Caveats: The evidence is mixed, with two meta-analyses showing significant benefit and one meta-analysis and one RCT showing no significant effect. The largest meta-analysis (n=2041) reported a neutral effect, suggesting that the overall benefit may be small or inconsistent. All studies were conducted in clinical populations; results may not generalize to healthy individuals. The median study duration was 169 days, indicating that effects may require long-term supplementation.

Generated Jul 15, 2026
Doses used in studies
  • g/day: 1 (median 1, IQR 11) 1 study
  • mg/day: 1,000 (median 1,000, IQR 1,0001,000) 1 study
Time to effect
Median: 5.6 months · IQR 4.2 months7 months · Range 2.8 months8.4 months — Reported in 2 of 4 studies
4 of 4 papers
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