Effect of L-carnitine on the lipid profile, glycemic control, oxidative stress, and anthropometric indices of individuals with type 2 diabetes: A systematic review

Diabetes mellitus is one of the most prevalent metabolic diseases in existence. With more than 536.6 million cases having been diagnosed globally, its prevalence is reported to be 10.5% in 2021. In individuals with diabetes, plasma L-carnitine is low and metabolized abnormally. In this review, we aimed to assess whether L-carnitine supplementation is correlated with a reduction of the risk of cardiovascular diseases in individuals with diabetes by improving the compositions of lipid profiles, indicators of oxidative stress, glycemic control, and anthropometric indices. A literature search in major databases such as Web of Science, PubMed, Google Scholar, Scopus, and Scientific Information Database was conducted until November 2021. This was done in conjunction with a search in Elsevier and SpringerLink databases, resulting in the inclusion of relevant articles in this review. To construct the search strategy, “Carnitine” OR “glycine propionyl carnitine” OR “Acetylcarnitine” in combination with “Diabetes Mellitus” OR “Diabetes Complications” OR “Lipid Profile” and all of its components were used to search for and within the articles and databases. After screening, 10 articles published between 1998 and 2017 were identified. They evaluated the effect of L-carnitine on lipid profile metabolism, glycemic control, anthropometric indices, and oxidative stress markers in individuals with diabetes. In this systematic review, we concluded that L-carnitine had no notable effect on lipid profile as well as glycemic control and anthropometric indices. Therefore, using L-carnitine probably has no notable effect on metabolic status in individuals with diabetes. Meanwhile, some articles suggested that L-carnitine may have positive effects on some oxidative stress indicators.