OBJECTIVES: To examine treatment intensification and switching patterns of individuals with T2DM initiating OHM. The results are compared to international guidelines issued in 2009. METHODS: Data were analysed using a population-based pharmacy claims database from 01/2008–11/2012. Incident users of OHM were identified for 2008-2009 as not having received OHM in the previous 12 months. Patients dispensed insulin, >one OHM, or <16 years were excluded from the study. Patients were followed until Nov-2012. Treatment intensification was defined as receiving an additional one, or two hypoglycaemic medicines (double or triple-therapy respectively). Treatment switching was defined as OHM monotherapy discontinuation with initiation on alternative monotherapy. RESULTS: 24,869 patients were included in the study. Most were initiated on metformin (76.4%) or sulphonylureas (21.6%). Treatment intensification: 25.8% of patients initiated on metformin progressed to double-therapy. Sulphonylureas (61.5%), DPP-4 inhibitors (23.9%) and GLP-1 agonists (6.2%) were the most frequently prescribed add-on treatment (median time to add-on OHM=424days). Of those initiated on sulphonylureas 32.4% progressed to double-therapy; metformin (78.4%), DPP-4 inhibitors (9.3%) and long-acting insulin (5%) were the most frequently prescribed (median time to add-on=295days). 14.3% of patients on double-therapy progressed to triple-therapy (median time to add-on=434days). 26.6% of patients did not receive the recommended double-therapy and 64.3% received agents in their triple-therapy that were not recommended. Treatment Switching: Overall 7.1% switched medication. The most frequent switches were metformin to sulphonylureas (46.5%, median time to switch=226days), sulphonylureas to metformin (22.5%, median time to switch=330days) and metformin to DPP-4 inhibitors (6.9%, median time to switch=577days). Initial OHM was significantly associated with time to switch (p<.0001). CONCLUSIONS: Initial drug treatment followed guidelines. However, evidence-based practice was not closely followed for treatment intensification suggesting prescribers may be unaware of treatment guidelines. This data may be useful for assessing the potential place in therapy, and cost-effectiveness of new hypoglycaemic medicines.