The main concern in Type 2 Diabetes Mellitus (T2DM) management is to control the glycaemic level and thus prevent complications by behavioural modifications as a part of the government’s national strategic plan. The patient should know about the disease for behavioural modification to be implemented. Thus, this study evaluated the level of knowledge among T2DM patients in primary healthcare in the West Coast Division of Sabah. This is a cross-sectional study conducted in 2015 involving 15 primary healthcare clinics. A validated Malaysian version of the Michigan Diabetes Knowledge Test (MDKT) questionnaire was used to assess patients’ diabetes knowledge. The mean age of 369 patients is 54.9 years old (SD = 11.04). The means of knowledge scores were significantly different among the age group, education level, and employment status. No significant differences in knowledge were found in the group regarding the duration of diabetes and glycaemic control. Of 369 diabetic patients, 26.3% had poor knowledge, 65.0% had adequate knowledge, and only 8.7% had good knowledge. Overall, patients with T2DM in primary healthcare clinics have adequate knowledge regarding diabetes. Our study’s findings indicate that patients’ knowledge is associated with age group, level of education, and employment status. Healthcare providers should plan a good strategy to educate their patients based on these differences.