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Evidence-Based Supplement Research
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L-Carnitine and Reduced Fasting Blood Glucose Levels

Research synthesisHigh evidenceSmall effect7 studies · 7 beneficial · 0 neutral · 0 harmful

Across 7 studies, all reported beneficial effects of L-carnitine on reducing fasting blood glucose, with predominantly small effect sizes. The evidence includes multiple meta-analyses and randomized controlled trials in clinical populations such as PCOS, overweight/obesity, and hemodialysis. Effects were typically observed at 8 weeks, with most doses converging around 2000–3000 mg/day in adults.

  • Effective dose range: 2000–3000 mg/day (adults); 50 mg/kg/day (pediatric)
  • Studied populations: Clinical populations with metabolic conditions (PCOS, overweight/obesity, type 2 diabetes, impaired glucose tolerance, hemodialysis)

Caveats: Available evidence is overwhelmingly positive — clinical literature in this area is subject to publication bias (null-result studies are less likely to be published or indexed). Effect sizes are consistently small, and the median study duration of 56 days is based on only 2 of 7 studies reporting duration. Most studies did not specify the form of L-carnitine, limiting conclusions about form-specific effects.

Generated Jul 15, 2026
Doses used in studies
  • L-Carnitine · mg/day: 3,000 (median 3,000, IQR 3,000–3,000) — 1 study
  • g/day: 2 (median 2, IQR 2–2) — 1 study
  • mg/kg/day: 50 (median 50, IQR 50–50) — 1 study
Time to effect
Median: 8 weeks · IQR 7 weeks–9 weeks · Range 6 weeks–10 weeks — Reported in 2 of 7 studies
7 of 7 papers
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