Background: Poor adherence is an obstacle in therapeutic control of diabetes. Despite the advances in the treatment of diabetes mellitus over the years, diabetes places an immense burden on the individuals living with the condition, their families and the overall health care system. Objective: Evaluation of the impact of medication adherence on the clinical outcomes of type 2 diabetes patients at Alimosho general hospital, Igando Lagos state. Method: The medication adherence study was both descriptive (retrospective) and prospective. The retrospective study assessed the prevalence of medication non-adherence leading to poor glycemic control. This involved the review of case notes of one-hundred and fifty two randomly selected patients. Prospective study was done by counselling and educating the patients on medication adherence and assessing their medication adherence and the impact of medication adherence on glycemic control. Results: The proportions of females/males with type 2 DM was found to be 69% and 31% respectively. 51.32% of these patients viewed their medications to be unaffordable. 56.6% of the patient population were 61 years and above in age. There was a significant relationship between patient age, gender and adherence to medication. There was however no significant P ≥ 0.05 association between educational level and adherence. Health education and counselling resulted in adherence rate and clinical parameters improvements. Conclusion: Non-adherence is a major factor that could lead to morbidity and mortality in diabetic patients. The overall improvement in adherence rate of 86.8% was observed with a decline in non-adherence rate after interventions.