Metformin discontinuation in patients beginning second-line glucose-lowering therapy: results from the global observational DISCOVER study programme

Abstract

ObjectivesTo evaluate the extent to which patients with type 2 diabetes discontinue metformin therapy when initiating second-line treatment and factors associated with metformin discontinuation, using baseline data from the DISCOVER study programme.DesignDISCOVER is a 3-year, prospective, observational study programme including data from 38 countries across 6 continents from 2014 to 2019.SettingPrimary and secondary healthcare centres, hospitals and specialist diabetes centres in both urban and rural locations.ParticipantsA total of 15 992 patients with type 2 diabetes initiating second-line glucose-lowering therapy.Primary and secondary outcome measuresThe proportion of patients who discontinued metformin as a second-line therapy and the factors associated with this treatment change.ResultsOf the 14 668 patients (from 37 countries) with valid treatment data, 11 837 (80.7%) received metformin as first-line glucose-lowering therapy; 8488 (71.7%) received metformin monotherapy and 3349 (28.3%) received metformin as part of a combination therapy. Overall, treatment with metformin was discontinued in 15.1% (1782) of patients who received first-line metformin (14.1% (1194) and 17.6% (588) in those who received metformin as monotherapy and as part of a combination, respectively); this proportion varied across regions from 6.9% (54) in Africa to 20.6% (628) in South-East Asia. On metformin discontinuation, 73.6% (1311) of patients received a non-insulin monotherapy at second line. Factors associated with an increased odds of metformin discontinuation were older age (≥75 years) and having a history of chronic kidney disease. The probability of metformin monotherapy discontinuation was lower in patients from Africa than in those from Europe.ConclusionsA substantial number of patients discontinued taking metformin when beginning second-line therapy. Most of these patients subsequently received a non-insulin monotherapy at second line, in contradiction to international guidelines and potentially leaving them at an increased risk of hyperglycaemia and associated adverse outcomes.Trial registration numbersNCT02322762 and NCT02226822.