Insulin therapy does not impact the effectiveness of anti-vascular endothelial growth factor (VEGF) for patients with type 2 diabetes, according to a study published in BMC Ophthalmology.

The incidence of diabetic macular edema (DME) is about 28% among patients who have had diabetes for more than 20 years. While glycemic control benefits patients with diabetes, prior studies have indicated insulin control of glycemia is associated with increased risk of DME and diabetic retinopathy (DR). Few studies have evaluated how insulin therapy impacts the effectiveness of anti-VEGF injection.

Researchers retrospectively evaluated patients (137 solely insulin or insulin and oral hypoglycemic agent (OHA) group 61 solely OHA group) from the Tasmanian Ophthalmic Biobank and the Genetic Risk Factors in Complications of Diabetes studies who began intravitreal anti-VEGF injections between 2013 and 2019 for the treatment of DME following T2 diabetes.


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The insulin group experienced longer DM (P <.001), more severe DR (P =.028), and poorer DM control (P =.033) compared with the OHA group. A higher portion of the insulin group had hypertension (P =.014) or nephropathy (P =.002) compared with the OHA group. More patients in the insulin group had received PRP laser therapy (P =.002). More in the OHA group had undergone cataract surgery (P =.019). About 55% of patients in the groups were taking bevacizumab. 

After a year of treatment, the insulin group (but not the OHA group) experienced significant improvement from baseline in best corrected visual acuity (BCVA) (P <.001). The groups had similar final BCVA after 1 year and experienced significantly reduced central macular thickness (CMT), without a significant difference in final CMT, number of injections received, change in vision, and change in CMT.

The investigators report that insulin therapy does not alter visual outcomes for patients with type 2  diabetes receiving anti-VEGF injections. “Patients do not need to alter their diabetes medication to optimize their eye care,” according to investigators. “Of key clinical relevance, we found no association between insulin treatment and suboptimal vision or CMT outcome. In fact, these patients showed significant improvements in both of these outcomes. As insulin improves glycemic control, it may even be positively associated with a better anti-VEGF response in the long term.”

Limitations of the study include retrospective observational design, small cohort size, and approximated conversion methods.

Reference

Gurung RL, FitzGerald LM, Liu E, et al. The effect of insulin on response to intravitreal anti‑VEGF injection in diabetic macular edema in type 2 diabetes. BMC Ophthalmol. Published online February 28, 2022. doi: 10.1186/s12886-022-02325-x