A randomized, open-label, multicentre, parallel-controlled study comparing the efficacy and safety of biphasic insulin aspart 30 plus metformin with biphasic insulin aspart 30 monotherapy for type 2 diabetes patients inadequately controlled with oral antidiabetic drugs: The merit study.

AIM: To confirm non-inferiority of biphasic insulin aspart 30 (BIAsp 30) plus metformin to BIAsp 30 in lowering glycated haemoglobin (HbA1c) in Chinese patients with inadequately controlled type 2 diabetes using oral antidiabetic drugs.

MATERIALS AND METHODS: In this 16-week, prospective, randomized, open-label, multicentre, parallel-controlled study, patients aged 18-79 years with HbA1c ≥7% were randomized to BIAsp 30 plus metformin (n = 130) or BIAsp 30 (n = 127). Initially, 500 mg metformin was administered twice daily and BIAsp 30 was administered at 0.2-0.3 U/kg/d. Changes in HbA1c % from baseline to week 16 as well as secondary and safety endpoints were assessed.

RESULTS: In total, 83.66% of patients in the BIAsp 30 plus metformin (n = 110) and the BIAsp 30 (n = 105) groups completed the study. Mean (±standard deviation) change in HbA1c from baseline to endpoint was -1.74 ± 1.64% and -1.32 ± 2.05% with BIAsp 30 plus metformin and BIAsp 30, respectively. Least squares mean treatment difference was -0.67% (95% CI, -1.06; -0.28). The upper limit of the 95% CI was <0.4 (non-inferiority margin). A significantly higher proportion of individuals reached HbA1c <7% with BIAsp 30 plus metformin than with BIAsp 30 (53.15% vs 35.19%; P = 0.0074). At endpoint, daily BIAsp 30 dose (P < 0.001) and weight gain were significantly lower (P < 0.05) in the BIAsp 30 plus metformin group compared with the BIAsp 30 group. No between-group differences in number of hypoglycaemic events were observed.

CONCLUSION: BIAsp 30 plus metformin was non-inferior to BIAsp 30 in safely reducing HbA1c in this study.