The study was carried out to determine the influence of knowledge and dietary compliance on the glycemic control and nutritional status of 50 patients with type 2 diabetes mellitus in OLA Catholic Hospital Ibadan, Nigeria. A semi-structured interviewer administered questionnaire was used to obtain information on the socio-demographic characteristics, knowledge about diabetes mellitus and dietary compliance of the respondents and anthropometric status of the respondents. Data collected were analyzed using descriptive and inferential statistical tools. Most of the respondents, 38 (76.0%) and 29 (58.0%) had poor overall knowledge score (< 50% score) and dietary compliance (< 50% score) respectively. Respondents’ knowledge and dietary compliance had significant influence on their biochemical status and anthropometric status (p< 0.05). Nutrition education to diabetic mellitus patients regarding diet, as well as patient compliance needs to be improved.