Ethnic disparity in metformin prescribing was uncovered in an investigation of metformin adherence in patients with type 2 diabetes. Prescription and dispensing data during the period from October 2016 to March 2018 were collected for 1595 patients from 10 general practices. The mean medication possession ratio was 0.87. Optimal medication cover for ≥80% of days was achieved by 63.8% of Māori vs 81.2% of European patients. Prescription adherence did not differ by ethnicity, but significantly fewer Māori patients received a prescription for metformin (p=0.002) leading to an overall reduction in metformin coverage for Māori patients. Adherence to metformin was associated with a 3.2 mmol/mol reduction in HbA1c (p<0.01).
