BACKGROUND : Teneligliptin, an antidiabetic agent classified as a class III dipeptidyl peptidase-4 (DPP-4) inhibitor, has a unique structural feature that provides strong binding to DPP-4 enzymes. We investigated the efficacy and safety of switching patients with type 2 diabetes mellitus (T2DM) who had inadequate glycemic control on a stable dose of other DPP-4 inhibitors to teneligliptin. METHODS : Patients with T2DM whose glycosylated hemoglobin (HbA1c) levels were ≥ 7% despite taking DPP-4 inhibitors other than teneligliptin, with or without other hypoglycemic agents, for at least 3 months were enrolled. The DPP-4 inhibitors taken before participating in the study were switched to 20 mg qd teneligliptin, and this was to be maintained for 52 weeks. The primary end point was the change in HbA1c levels after 12 weeks. Metabolic parameters including fasting plasma glucose (FPG) and blood lipids were assessed also. To assess safety, adverse and hypoglycemic events were monitored. The data from baseline to week 12 were used for analysis in this interim report. RESULTS : The mean change in HbA1c levels from baseline to week 12 was - 0.44%. At week 12, the percentage of patients achieving HbA1c < 7.0% was 31.6% and that of achieving HbA1c < 6.5% was 11.4%, respectively. In 41.2% of patients, the HbA1c levels decreased by at least 0.5% at 12 weeks. The mean change in FPG levels from baseline to week 12 was - 11.5 mg/dl. No severe hypoglycemia was reported. CONCLUSIONS : After switching to teneligliptin, HbA1c levels decreased significantly in patients with T2DM inadequately controlled with other DPP-4 inhibitors. BACKGROUND : ClinicalTrials.gov, NCT03793023. BACKGROUND : Handok Inc.