Clinical potential of treatment with semaglutide in type 2 diabetes patients

Glucagon-like receptor agonists (GLP-1RAs) are included in current national and international guidelines as second-line treatment especially in patients with type 2 diabetes and concomitant cardiovascular disease (CVD). First-generation GLP-1RAs were two- or once-daily injectables, but longer-acting GLP-1RAs have now been developed for once-weekly administration – e.g., exenatide ER, dulaglutide and semaglutide. With semaglutide, the same prolongation principle as designed in liraglutide is used (spacer and fatty acid chain). However, the similarity to endogenous human GLP-1 is well preserved, sharing 94% homology. It is administered with a simple device and without resuspension before use. The efficacy and safety of semaglutide have been investigated in an extensive clinical development program including more than 9,000 patients with type 2 diabetes. Semaglutide has been compared head-to-head with a dipeptidyl peptidase-4 (DPP4)-inhibitor, GLP-1RAs and basal insulin. Further head-to-head studies are awaiting that compare semaglutide against a sodium-dependent-glucose transporter-2 (SGLT2)-inhibitor. In these studies, semaglutide was found to provide significant and clinically relevant reductions in HbA1c, fasting plasma glucose (FPG), glucose excursions, body weight and blood pressure. The reduction in glycaemic parameters was more pronounced than that in the comparator GLP-1RAs. The rate of hypoglycemia is very low during treatment with semaglutide if not combined with sulphonylureas or insulin. A cardiovascular outcome trial (CVOT) was performed before the approval of semaglutide, at the request of legal authorities. Not only non-inferiority was confirmed, but also superiority compared with placebo used in a population of patients with type 2 diabetes and CVD treated with oral antihyperglycaemic drugs (OADs) and/or insulin with regard to the primary composite endpoint: death from cardiovascular (CV) causes, nonfatal myocardial infarction or nonfatal stroke. The safety of treatment with semaglutide in patients with type 2 diabetes has been extensively investigated. Overall, gastrointestinal side effects dominate, as observed with other GLP-1RAs, and was observed in the same range as for comparator GLP-1RAs. As observed with other GLP-1RAs, side effects such as nausea and vomiting diminished over time during continuous treatment. Regarding microvascular complications, an unexpected increase in diabetes-related retinopathy was observed in the CVOT; Semaglutide Unabated Sustainability in Treatment of Type 2 diabetes’ [SUSTAIN 6]), but not in other studies. The reason for this increase is not finally elucidated, but may be due to a nonspecific effect of a rapid decrease in glycaemic parameters in patients with preexisting retinopathy with high HbA1c at the start of the treatment. There is currently a warning in the Summary of Product Characteristics (SmPC) for semaglutide concerning treatment in patients with preexisting retinopathy. Further studies are needed to clarify this.