Background: The quality of life (QoL) describes the multidimensional self-perceived well-being of a person, which is an important diabetes outcome. This study aimed to measure the QoL scores among patients with type 2 diabetes mellitus (T2DM), as well as their clinical and sociodemographic predictors. Methods: This cross-sectional study involved 180 randomly sampled patients at a primary care clinic on the East Coast of Peninsular Malaysia. A self-administered questionnaire containing the Audit of Diabetes Dependent Quality of Life-18 (ADDQoL-18) was used. Results: Most of the respondents (96.7%) were Malay, with a median (interquartile range, IQR) age of 54.0 (14.0) years old. The majority of them were females (60.0%), married (81.1%) and from low-income families (63.3%), who attained a secondary education or lower (75.6%). Only 49.4% of them were employed. The mean (standard deviation, SD) ADDQoL-18 average weighted impact score was −4.58 (2.21) and all 18 domains were negatively affected, particularly the living condition, family life and working life. The multiple linear regression analysis showed that the age (adjusted B = 0.05, P = 0.004) and insulin use (adjusted B = −0.84, P = 0.011) were QoL predictors. Conclusion: T2DM negatively impacts the patient’s QoL in all aspects of their life. The QoL improvement with age suggests that the older patients had accepted and adapted to their illness. The need to improve the QoL among insulin users was also highlighted.