Background: Family functionality is a patient-oriented medical and pharmaceutical outcome of care that is emerging in scientific literature. It is a family-related factor that influences positively or negatively medication adherence and glycaemic control yet it is not easily recognized by physicians and physician assistants. Aim: The study was aimed at determining the role of family functionality on medication adherence and glycaemic control among ambulatory type 2 diabetic patients in a Nigerian hospital. Materials and Methods: A clinicbased descriptive study was carried out on 120 type 2 diabetic Nigerians who were on treatment for at least three months at the primary care clinic of a tertiary hospital in Nigeria. Family functionality and medication adherence were assessed in the previous three months and one month preceding the study using General Functioning sub-scale of the Family Assessment Device(FAD) and intervieweradministered questionnaire on self-reported adherence to therapy(SAT) respectively. Glycaemic control was assessed in the previous one month. Family functionality referred to the perception of behavior of family members in relation to day to day diabetes care decisions and their psycho-physical interactions. Results: Healthy family function, medication adherence and glycaemic control rates were 90.8%, 72.5% and 61.7% respectively. Family functionality was significantly associated with household family (.048), medication adherence (p=.031) and glycaemic control (p=.022). Conclusion: Family functionality was significantly associated with household family, medication adherence and glycaemic control. Assessment of family functionality should be part of reason for encounter during consultation with diabetic patients in order to unravel family factors that can positively or negatively influence medication adherence and glycaemic control.