Aims: Diabetes is a metabolic disorder, the effective management of which requires not only medication use but also patient diabetes knowledge for adopting necessary daily lifestyle changes. Those with better knowledge of diabetes management are expected to maintain well glycemic control. The aim of the study is to identify the extent of diabetes-related knowledge among people living with Type 2 diabetes mellitus. Study design: Descriptive cross-sectional comparative study. Place and Duration of Study: The study was carried out under the supervision of OPJS University and a field study was carried out in selected sub-metropolitan cities of Nepal from September 2019 to June 2020. Methodology: A simple random sampling technique was used comprising a structured questionnaire to examine the knowledge and practices of diabetes among 415 participants. This study reports the psychometric properties of the 24-items version of the Diabetes Knowledge Questionnaire which was already validated and used by the various researchers. However, to provide content validity, the draft form of the items will be again examined by one specialist in the subject. Descriptive statistics along with inferential statistics were calculated and a p<0.05 was considered significant for data analysis. Results: More than half 222(53.5%) of the male participants have poor glycemic control and 14% of them were obese. The results of the present study revealed that there was a significant relationship between the Diabetes Knowledge Questionnaire and basic information, glycemic control and prevention of complications. Conclusions: Based on the findings, the study concluded that there are many barriers to achieving glycemic control, the most significant barrier was found to be inadequate knowledge and understanding about diabetes mellitus among people with type 2 diabetes mellitus.