Background: Type 2 Diabetes Mellitus (T2DM) remains a significant cause of death globally. In addition, T2DM is among the top five chronic diseases which leads to mortality in the Thai population. Patients with T2DM need a wide self-management protocol.  However, patients with low health literacy experience difficulty in recognizing health-related information and have difficulties in expressing their status to health care providers, resulting in poor self-management which results in worsening of the health condition. This study aimed to identify the health literacy among patients with type 2 diabetes to determine its association between factors with blood sugar level control in the patients who are treated in primary care units. Methods: A total of 605 subjects were randomly selected from four districts of Nakhon Ratchasima Province, Northeastern Thailand. Data were collected using a structured questionnaire and a review of their charts. A descriptive statistical analysis was used to describe characteristics of the subjects. In addition, multiple logistic regression was used for the association to estimate effect sizes in terms of an odds ratio with the 95% confidence interval. Results: Of the total 605 respondents, 90.90% of the subjects had a sufficient level of health literacy about diabetes. The present study found the subjects who had sufficient health literacy were significantly associated with blood sugar level control (Adjusted Odds Ratio, (AOR)=2.27; 95% CI: 1.10-4.74; p =0.026). A strongly significant association with blood sugar level control was found with diet behaviors (AOR = 9.71; 95% CI: 5.98-15.77; p<0.001) and exercise behaviors (AOR = 14.50; 95% CI: 8.66-24.27; p<0.001). Conclusions: Health literacy on the changing health related behaviors among the T2DM patients is significantly associated with controlling blood sugar level. Hence, health practitioners should enhance the health literacy on self-care among T2DM patients which will help to control T2DM in an effective manner.