The aim of this study was to compare the levels of 25(OH) Vitamin D in patients with type 2 diabetes mellitus (T2DM), taking oral hypoglycemic (OHA) medications and insulin. The study is based on data from 126 T2DM patients and 62 healthy controls admitted to the Policlinic of Endocrinology in the Department of Internal Medicine and Polyclinic of Family Medicine in the Education and Research Hospital of Faculty of Medicine, Eski?ehir Osmangazi University, between October 1, 2013 and April 30, 2014. In order to accomplish the aim of this study, HbA1C, lipid profile, and 25(OH) vitamin D levels of the patients were determined simultaneously. The 25(OH) vitamin D levels of participants in the control group (22.371 ± 13.888) were higher than those of the patients in the OHA group. 25(OH) vitamin D levels of participants in the control group (22.371 ± 13.888) were also higher than the levels of patients in the insulin group (10.177 ± 6.188). The level of 25(OH) Vitamin D was higher in the OHG group; however, the difference was not significant (p=0.189). 25(OH) vitamin D levels of the insulin-taking group were lower than the OHA-taking group and control group due to the increase of insulin resistance. Considering that diabetes plays a role in organ damage and other dysfunctions, the cost-effective and easy treatment with Vitamin D becomes more important.