OBJECTIVES: Add-on medications are recommended if target glycemic goals for patients with T2DM are not achieved or sustained after initial metformin monotherapy. This study examined the time to add-on medication use after metformin monotherapy failure in clinical practice. METHODS: Selected from a large US EMR database between Janujary 1, 1997 and December 31, 2008, included patients had to be aged ≥18 years with a diagnosis of T2DM who had HbA1c ≥7.0% or ≥ two fasting blood glucose levels of 126mg/dL or greater. Treatment failure was defined as HbA1c ≥7% (index date) after metformin monotherapy for at least 6 months. Baseline data were extracted during 1 year prior to the index date. Time to add-on medication use was time between index date to the first add-on medication use during follow-up and was evaluated for the overall cohort and for three index HbA1c subgroups: <8%, 8-9%, and >9%. A Cox proportional hazard model was employed to determine baseline clinical and demographic characteristics associated with shorter time to add-on medication use. RESULTS: There were 12,566 patients meeting the inclusion criteria; 8656, 2175 and 1735 had index HbA1c <8%, 8-9% and >9%, respectively. The overall mean (SD) age was 63 (12) years and 51% were female. The median time to add-on medication use was 15.7 months overall and 17.0, 13.9 and 11.3 months for patients with index HbA1c <8%, 8-9% and >9%, respectively. Higher index A1c, greater body mass index, higher Charlson comorbidity index, younger age, males, lower LDL were significantly associated with shorter time to add-on medication use (all p<0.05). CONCLUSIONS: This indicates, in US clinical practice, it takes over a year for a diabetic patient who has sub-optimal glycemic level after initial metformin monotherapy to receive add-on medications. There is room through disease management so that patients who have failed metformin monotherapy, if eligible and appropriate, receive add on therapy sooner rather than later.