Purpose: This study used raw data from the fifth (2010-2012) Korea National Health and Nutrition Examination Survey (KNHANES) to assess the relationship between vitamin D level and glycemic control of diabetes, and to provide basic data about the use of vitamin D for preparation of a treatment plan for diabetes in South Korea. Methods: For this study, data of 1,713 diabetes from KNHANES (2010-2012) were used. The collected data were analyzed using SPSS 18.0 program, and complex sample frequency analysis, descriptive statistics, complex sample cross analysis, complex sample general linear regression, and complex sample logistic regression analysis were performed. Results: It was found that the poor glycemic control group among the diabetes subjects had ignificantly lower level of blood vitamin D than the good glycemic control group. Factors affecting glycemic control included drinking, vitamin D levels, hypertriglyceridemia, duration of diabetes, and treatment of diabetes. Also, diabetics with vitamin D deficiency or shortage showed 3.55- and 2.61-times higher odds ratios, respectively, to be diagnosed as the poor glycemic control group than diabetics without vitamin D deficiency or shortage. Conclusion: This study is significant because it provides rationale and basic data about the use of vitamin D for preparation of a treatment plan for diabetes in South Korea by assessing the dependence of glycemic control on the vitamin D level of diabetics. Additionally, future studies are necessary to determine the appropriate concentration of itamin D for diabetes prevention and treatment to prevent the side effects of excessive supplementation.