en تخصصي Special پژوهشي Research <strong>Objective:</strong> Due to the lack of information about the positive or negative effects of L-carnitine, chromium, vitamin D, and the uptake of a safe dietary supplement to reduce the effects of diabetes, it seems essential to determine the effects of these drugs on diabetes.<br> <strong>Materials and Methods</strong><strong>:</strong> Wistar rats were divided into 12 groups, control, diabetic, and intact, each of which was treated with metformin, L-carnitine, vitamin D, and chromium or a combination of L-carnitine, vitamin D, and chromium. The serum levels of liver function parameters, iron, TIBC, Catalase and GPX activities were measured. Data were statistically analyzed by one-way ANOVA using SPSS 18 software. Statistical significance among the groups was determined using LSD test, and <em>P</em>-value< 0.05 was considered significant in all cases.<br> <strong>Results:</strong> AST activity in diabetic groups and those receiving chromium and L-carnitine has significantly reduced (<em>P</em><em>-</em>value= 0.009). A significant reduction in ALT and ALP activity in the diabetic groups receiving vitamin D and combined and non-diabetic groups receiving metformin were observed, in contrast to a significant increase in ALT activity in diabetic recipients of L-carnitine (<em>P</em><em>-</em>value= 0.009).<br> <strong>Conclusion</strong><strong>:</strong> L-carnitine, chromium, and vitamin D supplements have synergistic effects and a combination of them has the best protective effect on factors that have been studied. Diabetes mellitus, L-carnitine, Chromium, Vitamin D, Metformin 82 87 http://ijdo.ssu.ac.ir/browse.php?a_code=A-10-30-308&slc_lang=en&sid=1 Parisa Sheikh Samani 0000-0001-8985-1036 No Department of Biochemistry, Falavarjan Branch, Islamic Azad University, Isfahan, Iran. Kahin Shahanipour 0000-0002-6627-6873 Yes Department of Biochemistry, Falavarjan Branch, Islamic Azad University, Isfahan, Iran. Ali Noori Diziche 0000-0003-3083-6602 No Department of Biology, Falavarjan Branch, Islamic Azad University, Isfahan, Iran. Mohammad Adibnejad 0000-0002-1159-2641 No Department of Biochemistry, Falavarjan Branch, Islamic Azad University, Isfahan, Iran.