Combination therapy of oral hypoglycemic agents in patients with type 2 diabetes mellitus

The Korean Diabetes Association (KDA) recently updated the Clinical Practice Guidelines on antihyperglycemic agent therapy for adult patients with type 2 diabetes mellitus (T2DM). In combination therapy of oral hypoglycemic agents (OHAs), general recommendations were not changed from those of the 2015 KDA guidelines. The Committee on Clinical Practice Guidelines of the KDA has extensively reviewed and discussed the results of meta-analyses and systematic reviews of effectiveness and safety of OHAs and many clinical trials on Korean patients with T2DM for the update of guidelines. All OHAs were effective when added to metformin or metformin and sulfonylurea, although the effects of each agent on body weight and hypoglycemia were different. Therefore, selection of a second agent as a metformin add-on therapy or third agent as a metformin and sulfonylurea add-on therapy should be based on the patient's clinical characteristics and the efficacy, side effects, mechanism of action, risk of hypoglycemia, effect on body weight, patient preference, and combined comorbidity. In this review, we address the results of meta-analyses and systematic reviews, comparing the effectiveness and safety among OHAs. It will help to choose the appropriate drug for an individual patient with T2DM.