Semaglutide, reduction in HbA1c and the risk of diabetic retinopathy

AIMS: To evaluate diabetic retinopathy data from across the SUSTAIN clinical trial programme.

MATERIALS AND METHODS: The SUSTAIN clinical trial programme evaluated the efficacy and safety of semaglutide, a glucagon-like peptide-1 analogue, for the treatment of type 2 diabetes (T2D). In SUSTAIN 6 - a 2-year, preapproval cardiovascular outcomes trial - semaglutide was associated with a significant increase in the risk of diabetic retinopathy complications (DRC) versus placebo. Diabetic retinopathy (DR) data from across the SUSTAIN trials were evaluated and post hoc analyses of the SUSTAIN 6 data were conducted. These included subgroup analyses to identify at-risk patients and a mediation analysis with initial change in HbA1c (percentage-points at Week 16) as a covariate, to examine the role of the magnitude of reduction in HbA1c as an intermediate factor on risk of DRC.

RESULTS: There was no imbalance in DR adverse events across the SUSTAIN 1-5 and Japanese trials. The majority of the effect with semaglutide versus placebo in SUSTAIN 6 may be attributed to the magnitude and rapidity of HbA1c reduction during the first 16 weeks of treatment in patients with pre-existing DR, poor glycaemic control at baseline, and treated with insulin.

CONCLUSIONS: Early worsening of DR is a known phenomenon associated with the rapidity and magnitude of improvement in glycaemic control with insulin; the DRC findings in SUSTAIN 6 are consistent with this. Guidance regarding the early worsening of DR is recommended with insulin; similar recommendations may be appropriate for semaglutide.