Addition of sulphonylurea to metformin does not relevantly change body weight: a prospective observational cohort study (ZODIAC‐39)

AIM: To investigate changes in body weight trajectories after the addition of individual sulphonylureas (SUs) to metformin in patients with type 2 diabetes. MATERIALS AND METHODS: We conducted a retrospective observational cohort study, in a primary care setting in the Netherlands. Patients aged ≥18 years with type 2 diabetes who were included in the ZODIAC cohort between 1998 and 2012 and who received metformin monotherapy at inclusion (n = 29 195), and had used metformin as monotherapy for at least 1 year before receiving dual therapy through the addition of an SU for at least 1 year were eligible for inclusion. The primary outcome was within‐drug yearly change in body weight after receiving add‐on therapy with individual SUs during 5 years of follow‐up. The secondary outcome was within‐drug yearly change in glycated haemoglobin (HbA1c). Annual changes in weight and HbA1c were estimated with linear mixed models, adjusted for age, gender and diabetes duration. RESULTS: A total of 2958 patients were included. No significant weight changes were observed within and between any of the individual SUs after treatment intensification (p = 0.24). In addition, no significant difference in weight between the add‐on therapy combinations was observed (p = 0.26). The average HbA1c the year before intensification was 7.2% (55 mmol/mol) and dropped below 7.0% (53 mmol/mol) the year after. CONCLUSIONS: In patients with type 2 diabetes treated in primary care, strict glycaemic control can be maintained with SUs used as add‐on therapy to metformin, without the offset of relevant weight changes.