Can L-carnitine improve glycemic control? Original paper

In this meta-analysis of randomized controlled trials, supplementation with L-carnitine improved measures of glycemic control in adults.

The effects of supplemental L-carnitine on glycemic markers, including serum insulin, fasting blood glucose, glycated hemoglobin (HbA1c), and the Homeostatic Model Assessment for Insulin Resistance (HOMA-IR).

2,900 adults (age range of 18–101).

The researchers performed a systematic review and meta-analysis of 41 randomized controlled trials. The included studies used daily doses of 0.25–4 grams of L-carnitine, and the duration of supplementation was 2–52 weeks.

The researchers also conducted subgroup analyses to investigate whether the study duration, intervention dose, BMI of the participants, the presence of diabetes, or baseline levels of fasting blood glucose influenced the outcomes.

Supplemental L-carnitine improved several markers of glycemic control, including fasting blood glucose (−3.22 mg/dL), HbA1c (−0.27%), and HOMA-IR (−0.73).

Subgroup analysis revealed that these beneficial effects of L-carnitine were stronger if taken for longer durations (≥12 weeks) and in higher doses (≥2 grams) and in participants with obesity, diabetes, or elevated levels of fasting blood glucose (≥100 mg/dL) at baseline.

Most studies included in the meta-analysis were at moderate (11 studies) and high (22 studies) risk of bias, which reduces confidence in the results.