Safety and tolerability of once-weekly GLP-1 receptor agonists in type 2 diabetes

What is known and objective: In recent years, glucagon-like peptide-1 receptor agonists (GLP-1 RAs) including once-weekly (QW) formulations have been incorporated into type 2 diabetes (T2D) clinical guidelines, making it essential that pharmacists and healthcare professionals (HCPs) have a clear understanding of their safety profiles. Currently, three QW GLP-1 RAs are approved and marketed in the United States for the treatment of T2D: dulaglutide, exenatide extended-release and semaglutide. This review provides pharmacists and HCPs with collated data related to potential safety and tolerability issues when patients use QW GLP-1 RAs, enabling patient education and treatment optimization.

Methods: This is a narrative review comparing the safety and tolerability of the three QW GLP-1 RAs, using data from Phase 3 clinical trials. Extracted safety data included gastrointestinal (GI) adverse events (AEs), hypoglycaemia, injection-site reactions, pancreatitis, neoplasms, gallbladder events, and diabetic retinopathy (DR) and/or its complications (DRCs).

Results and discussion: A total of 30 trials were identified for inclusion; eight were head-to-head trials involving another GLP-1 RA; of these, six compared GLP-1 RAs with different dosing regimens (QW vs once-daily or twice-daily), and two were direct QW vs QW GLP-1 RA comparisons. The most commonly reported AEs were GI events (notably nausea, vomiting and diarrhoea), but there was variation between the three QW drugs. These were generally mild-to-moderate in severity and transient. Risk of hypoglycaemia, injection-site reactions, pancreatitis, neoplasms and gallbladder events was generally low across the GLP-1 RAs investigated. Overall rates of DR or DRC were low across the trials. Only in one trial (SUSTAIN 6) there were significantly more DRC events reported in patients treated with QW semaglutide (3.0%) compared with placebo (1.8%). This was likely due to the rapid improvement in glucose control in patients with pre-existing DR enrolled within that trial.

What is new and conclusion: This review puts the latest clinical data from the marketed QW GLP-1 RAs into context with results from older Phase 3 trials, to enable pharmacists and HCPs to make informed treatment decisions. Each of the three QW GLP-1 RAs has their own safety profile, which should be considered when choosing the optimal treatment for patients.

Keywords: GLP-1 RA; dulaglutide; exenatide; safety; semaglutide; tolerability; type 2 diabetes.