Objective: The objective of this study is to assess the knowledge and self-care practices of people living with type 2 diabetes mellitus (T2DM). Materials and Methods: The study was conducted in a clinic in Southwestern Nigeria. It adopted a cross-sectional design. The sample consists of 107 people living with T2DM. Data were collected using Diabetes Knowledge Questionnaire and Revised Self-care Inventory Scale. Results: The mean diabetes knowledge of the participants was 16.2 ± 3.0 and 70.1% had inadequate knowledge of T2DM. The mean diabetes self-care practice score among the participants was 49.9 ± 4.9, and 89.7% reported poor diabetes self-care practice. There is no significant difference in the knowledge of diabetes between male (16.42 ± 3.42) and female (16.12 ± 2.8) participants (t = 0.45; P = 0.65), and no significant difference in self-care practice of male (49.23 ± 4.51) and female (50.06 ± 5.07) participants (t = 0.75, P = 0.46). In addition, there is no correlation between age and knowledge of diabetes (r = -0.18, P = 0.07) and self-care practices (r = 0.08, P = 0.38) of participants. No significant relationship was found between knowledge of diabetes and diabetes selfcare practices (χ2 = 1.605, P = 0.448) Conclusion: Knowledge of diabetes and self-care practices of people living with T2DM in this study were poor. Effort should be directed at improving their diabetes knowledge and self-care practices.