Aims:  To evaluate the efficacy and safety of alogliptin, a new dipeptidyl peptidase-4 inhibitor, for 26 weeks at once-daily doses of 12.5 and 25 mg in combination with metformin in patients whose HbA1c levels were inadequately controlled on metformin alone.

Methods and patients:  Patients with type 2 diabetes and inadequate glycaemic control (HbA1c 7.0-10.0%) were randomised to continue a stable daily metformin dose regimen (≥ 1500 mg) plus the addition of placebo (n = 104) or alogliptin at once-daily doses of 12.5 (n = 213) or 25 mg (n = 210). HbA1c, insulin, proinsulin, C-peptide and fasting plasma glucose (FPG) concentrations were determined over a period of 26 weeks.

Results:  Alogliptin at either dose produced least squares mean (SE) decreases from baseline in HbA1c of −0.6 (0.1)% and in FPG of −17.0 (2.5) mg/dl [−1.0 (0.1) mmol/l], decreases that were significantly (p < 0.001) greater than those observed with placebo. The between treatment differences (alogliptin – placebo) in FPG reached statistical significance (p < 0.001) as early as week 1 and persisted for the duration of the study. Overall, adverse events (AEs) observed with alogliptin were not substantially different from those observed with placebo. This includes low event rates for gastrointestinal side effects and hypoglycaemic episodes. There was no dose-related pattern of AE reporting between alogliptin groups and few serious AEs were reported.

Conclusion:  Alogliptin is an effective and safe treatment for type 2 diabetes when added to metformin for patients not sufficiently controlled on metformin monotherapy.