Differences in the glucose-lowering efficacy of dipeptidyl peptidase-4 inhibitors between Asians and non-Asians: a systematic review and meta-analysis

The aim of this work was to compare the glucose-lowering efficacy of dipeptidyl peptidase-4 (DPP-4) inhibitors between Asian and non-Asian patients with type 2 diabetes. We searched MEDLINE, EMBASE, LILACS, CENTRAL, ClinicalTrials.gov and conference proceedings. Studies were eligible if they were randomised controlled trials with a treatment duration of at least 12 weeks, compared a DPP-4 inhibitor with a placebo as either monotherapy or oral combination therapy, had information on ethnicity and HbA(1c) values and were published or described in English. A systematic review and meta-analysis with a meta-regression analysis was conducted. Among 809 potentially relevant studies, 55 trials were included. A meta-analysis revealed that DPP-4 inhibitors lowered HbA(1c) to a greater extent in studies with a parts per thousand yen50% Asian participants (weighted mean difference [WMD] -0.92%; 95% CI -1.03, -0.82) than in studies with < 50% Asian participants (WMD -0.65%; 95% CI -0.69, -0.60). The between-group difference was -0.26% (95% CI -0.36, -0.17, p < 0.001). The baseline BMI significantly correlated with the HbA(1c)-lowering efficacy of DPP-4 inhibitors. The RR of achieving the goal of HbA(1c) < 7.0% (53.0 mmol/mol) was higher in studies with a parts per thousand yen50% Asian participants (3.4 [95% CI 2.6, 4.7] vs 1.9 [95% CI 1.8, 2.0]). The fasting plasma glucose-lowering efficacy was higher with monotherapy in the Asian-dominant studies, but the postprandial glucose-lowering efficacy and changes in body weight were comparable between the two groups. DPP-4 inhibitors exhibit a better glucose-lowering efficacy in Asians than in other ethnic groups; this requires further investigation to understand the underlying mechanism, particularly in relation to BMI.