Chromium supplementation and type 2 diabetes mellitus: an extensive systematic review

Diabetes is a global public health concern with increasing prevalence worldwide. Chromium (Cr), a trace element found in soil, water, and food, has been proposed to have a possible positive effect in glucose metabolism and diabetes mellitus prevention. However, the relationship between trivalent chromium [Cr(III)] exposure, mainly through the consumption of diet supplements, and type 2 diabetes mellitus (T2DM) remains controversial. An extensive systematic review of the current literature on randomized controlled studies (RCTs) was conducted from 1 January 2000, to January 2024 using the databases PubMed, Scopus, ScienceDirect, and Cochrane, with specific keywords and inclusion as well as exclusion criteria. After close screening of the research studies retrieved from the mentioned websites was conducted, the most related studies were included in the final systematic review. The studies were evaluated for the degree of relevance, quality, and risk bias, using appropriate quality assessment tools. Several of the included RCT studies reported possible benefits of Cr(III) supplementation, mainly in the form of chromium picolinate (CrPic), chromium yeast (CY), chromium chloride (CrCl₃), and chromium nicotinate (CrN). The dosage of chromium was between 50 and 1000 μg/day and it was consumed from 2 to 6 months. Glycemic control markers, including FPG, insulin, HbA1C, and HOMA-IR levels, significantly decrease following chromium supplementation, mainly in studies with a longer intervention period. Supplementing with chromium (Cr) indicated that could significantly improve lipid profile by raising high-density lipoprotein and lowering triglyceride and total cholesterol while having little effect on low-density lipoprotein. However, most research findings include significant limitations, such as inconsistent dosage and type of chromium, formulation of supplements, and study duration. Further well-designed and high-quality research is needed to fully understand the role of chromium dietary supplementation and the potential risks related to its mechanisms of action, type, and dose, in the prevention and treatment of type 2 diabetes mellitus.