The effects of L-carnitine supplementation on cardiovascular risk factors in participants with impaired glucose tolerance and diabetes: a systematic review and dose–response meta-analysis

L-carnitine plays a role related to cardiometabolic factors, but its effectiveness and safety in CVD are still unknown. We aim to assess the effect of L-carnitine supplementation on CVD risk factors.

A systematic literature search was conducted in PubMed, Web of Science, and Scopus until October 2022. The main outcomes were lipid profiles, anthropometric parameters, insulin resistance, serum glucose levels, leptin, blood pressure, and inflammatory markers. The pooled weighted mean difference (WMD) was calculated using a random-effects model.

We included the 21 RCTs (n = 2900) with 21 effect sizes in this study. L-carnitine supplementation had a significant effect on TG (WMD = − 13.50 mg/dl, p = 0.039), LDL (WMD = − 12.66 mg/dl, p < 0.001), FBG (WMD = − 6.24 mg/dl, p = 0.001), HbA1c (WMD = -0.37%, p = 0.013) HOMA-IR (WMD = -0.72, p = 0.038 (, CRP (WMD = − 0.07 mg/dl, P = 0.037), TNF-α (WMD = − 1.39 pg/ml, p = 0.033), weight (WMD = − 1.58 kg, p = 0.001 (, BMI (WMD = − 0.28 kg/m², p = 0.017(, BFP (WMD = − 1.83, p < 0.001) and leptin (WMD = − 2.21 ng/ml, p = 0.003 (in intervention, compared to the placebo group, in the pooled analysis.

This meta-analysis demonstrated that administration of L-carnitine in diabetic and glucose intolerance patients can significantly reduce TG, LDL-C, FBG, HbA1c, HOMA-IR, CRP, TNF-α, weight, BMI, BFP, and leptin levels.

PROSPERO registration code: CRD42022366992.