Efficacy and safety of initial combination therapy with gemigliptin and metformin compared with monotherapy with either drug in patients with type 2 diabetes: A double-blind randomized controlled trial (INICOM study)

Background: Gemigliptin is a new dipeptidyl peptidase-IV inhibitor. We investigated the efficacy and safety of initial combination therapy with gemigliptin and metformin compared with monotherapy with either drug in patients with type 2 diabetes (T2D). Methods: A total of 433 T2D patients with a glycosylated haemoglobin (HbA1c) level of 7.5% to 11.0% and a fasting plasma glucose (FPG) concentration <270 mg/dL were randomly assigned to 3 groups: (1) gemigliptin 50 mg qd + metformin 1000 to 2000 mg qd (titrated individually), (2) gemigliptin 50 mg qd, or (3) metformin 1000 to 2000 mg qd. The primary end-point was the change in HbA1c level after 24 weeks. Secondary end-points were the changes in FPG, insulin, proinsulin and C-peptide levels. The percentages of responders who achieved an HbA1c level <7% (or <6.5%) were compared between treatment groups. Results: Baseline HbA1c levels were 8.7% in all groups. The mean changes in HbA1c level from baseline to week 24 were −2.06%, −1.24% and −1.47% in the combination, gemigliptin monotherapy and metformin monotherapy groups, respectively. The 95% confidence intervals for between-group differences in HbA1c changes were −1.02 to −0.63 in the combination group vs the gemigliptin group and −0.82 to −0.41 vs the metformin group, which confirmed the superiority of combination therapy. A significantly higher percentage of patients in the combination therapy group reached the target HbA1c level <7% (or <6.5%) compared with the monotherapy groups. No severe side effects were observed. Conclusions: In T2D patients, the initial combination of gemigliptin and metformin had superior efficacy without safety concerns compared with monotherapy with either drug.