Background: Diabetes mellitus (DM) patients are at increased risk of developing drug therapy problems (DTPs). The patients had a variety of comorbidities and complications, and they were given multiple medications. Medication therapy management (MTM) is a distinct service or group of services that optimize therapeutic outcomes for individual patients. The study assessed the impact of provision of MTM service on selected clinical and humanistic outcomes of diabetes patients at the diabetes mellitus clinic of Tikur Anbessa Specialized Hospital (TASH). Methods: A pre-post interventional study design was carried out at DM clinic from July 2018 to April 2019. The intervention package included identifying and resolving drug therapy problems, counseling patients in person at the clinic or through telephone calls, and providing educational materials for six months. This was followed by four months of post-intervention assessment of clinical outcomes, DTPs, and treatment satisfaction. The interventions were provided by pharmacist in collaboration with physician and nurse. The study included all adult patients who had been diagnosed for diabetes (both type I & II) and had been taking anti-diabetes medications for at least three months. Patients with gestational diabetes, those who decided to change their follow-up clinic, and those who refused to participate in the study were excluded. Data were analyzed using Statistical Package for the Social Sciences (SPSS). Descriptive statistics, t-test, and logistic regressions were performed for data analyses. Results: Of the 423 enrolled patients, 409 fulfilled the criteria and included in the final data analysis. The intervention showed a decrease in average hemoglobin A1c (HbA1c), fasting blood sugar (FBS), and systolic blood pressure (SBP) by 0.92%, 25.04 mg/dl, and 6.62 mmHg, respectively (p<0.05). The prevalence of DTPs in the pre- and post-intervention of MTM services was found to be 72.9% and 26.2%, respectively (p<0.001). The overall mean score of treatment satisfaction was 90.1(SD, 11.04). Diabetes patients of age below 40 years (92.84 (SD, 9.54)), type-I DM (93.04 (SD, 9.75)) & being on one medication regimen (93.13(SD, 9.17)) had higher satisfaction score (p<0.05). Conclusion: Provision of MTM service had a potential to reduce DTPs, improve the clinical parameters, and treatment satisfaction in the post-intervention compared to the pre-intervention phase.
