OBJECTIVES: The lack of adherence to diabetic drugs may reduce the effectiveness of the treatment increasing the hospitalization rates and costs. The purpose of this study is to estimate the economic savings derived from comparing different diabetic drug adherence scenarios at the Mexican Institute of Social Security (IMSS). METHODS: For patients with non-complicated diabetes mellitus, 19 pharmacological treatment patterns and their distribution were identified by a panel of experts from primary medical units and general and specialized hospitals. The total population of diabetic patients at IMSS in the year 2010 was obtained from the diabetes census; the percentage of patients under pharmacological treatment came from the institutional health survey of 2010. Four drug adherence scenarios derived from institutional studies were considered. All-cause hospitalization rates among diabetes drug adherent and non-adherent patients were derived from the international literature due to the lack of national estimations. The annual total costs included the pharmacological and all-cause hospitalization estimates for each treatment pattern. The exchange rate was $12.34 pesos per dollar. RESULTS: The metformin-glibenclamide combination was the most prescribed pharmacological treatment at the Institute (26.6%) followed by metformin-insulin NPH (11.8%) and metformin (11.2%). The diabetic drug adherence baseline scenario was 16%; this was compared with three scenarios of 17.2%, 27% and 54.2% respectively. The annual total costs were 6.05 times greater in non-adherent compared with adherent patients in the baseline scenario. The economic savings increases as the level of compliance scales up. This can be attributed to the cost reductions compared to non-adherent patients mainly due to hospitalization. In the year 2010, savings varied from USD$1.48 million to USD$47.01 million. CONCLUSIONS: Health policies that aim to increase adherence to diabetic drugs among patients are needed at the institution in order to avoid unnecessary costs mainly among non-adherent patients.