Authors reviewed 37 RCTs investigating L-carnitine supplementation on glycemic regulation. This meta-analysis was published in 2019 and reviewed studies published between 1998 and 2018 of which 37 RCT’s met inclusion criteria (total pooled 2467 subjects, 1243 in intervention and 1224 in control groups.) Intervention length varied from 23 days to 12 months and dosages ranged from 200 mg/day to 3,000 mg/day. L-carnitine supplementation resulted in a significant reduction in FPG, insulin, HOMA-IR, and HbA1C concentrations (particularly in patients >45yo.
Fathizadeh H, Milajerdi A, Reiner Ž, Kolahdooz F, Asemi Z. The effects of L-carnitine supplementation on glycemic control: a systematic review and meta-analysis of randomized controlled trials. EXCLI J. 2019;18:631-643. Published 2019 Aug 19. doi:10.17179/excli2019-1447 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6785772/