Introduction: Diabetes mellitus is a non-communicable disease with a high incidence in various countries, including Indonesia. Poor levels of sugar control are the cause of complications of diabetes mellitus. Diabetes knowledge is one of the keys to assist in controlling blood sugar levels in diabetes mellitus patients. Objective: This research assesses the associations between diabetes knowledge and glycemic control among diabetes mellitus patients in Garut District, Indonesia. Methode: The research method was designed using a cross-sectional with a number of sample 54 responded. data take with structured self-report interviews based on validated instruments for assessing diabetes knowledge and observation sheet to monitor blood sugar levels to assess glycemic control. The diabetes knowledge instrument contains questions about the concept of diabetes and management of diabetes in general. Glycemic control was measured by the value of blood sugar once a week for 4 weeks. Chi-Square statistical test was used to analyze the data. Results: The research findings that 19 respondents had good knowledge and controlled blood sugar levels. 35 respondents with insufficient knowledge where 31 respondents had uncontrolled blood sugar levels and 4 respondents had controlled blood sugar levels. Chi-Square test finds a significant probability (p= 0.000), there was a relationship between diabetes knowledge and Glycemic control. Conclusion: Diabetes knowledge is the important factors associated with glycemic control. Education for patients diabetes mellitus are suggested to improve control glycemic diabetes patient.