BackgroundDespite the increasing prevalence of type 2 diabetes mellitus (T2DM) in Asia, clinical trials for glucose-lowering therapies are often dominated by Caucasian and/or Western populations. The present Phase III randomized placebo-controlled double-blind, 24-week study evaluated the efficacy and safety of the dipeptidyl peptidase-4 inhibitor linagliptin added to metformin in Asian T2DM patients. MethodsIn all, 306 patients (n=265 Chinese; n=24 Malaysian; n=17 Filipino), aged 18-80 years with HbA1c between 7.0 and 10.0% and on metformin therapy were randomized (2:1) to either linagliptin 5mg daily or placebo added to metformin. Antidiabetes drugs other than metformin were washed out prior to randomization. The primary endpoint was change in mean HbA1c from baseline after 24 weeks. ResultsBaseline characteristics were well-matched between the groups (overall mean [SD] HbA1c 8.00.8%). Adjusted mean (SE) HbA1c decreased in the linagliptin and placebo groups by -0.660.05 and -0.140.07%, respectively (placebo-corrected difference -0.52 +/- 0.09%; 95% confidence interval [CI] -0.70, -0.34; P<0.0001). In patients with baseline HbA1c 8.5%, the placebo-corrected decrease in HbA1c was -0.89 +/- 0.17% (P<0.0001). Adverse events occurred in similar proportions in the linagliptin and placebo patients (27.3% and 28.0%, respectively) and few were considered drug-related (2.4% and 0.0%, respectively). Hypoglycemia occurred in 1.0% of patients in both groups. Linagliptin therapy was weight neutral. ConclusionsLinagliptin 5mg was efficacious and well tolerated over 24 weeks in Asian patients with T2DM inadequately controlled by metformin.