New anti-hyperglycaemic agents for type 2 diabetes and their effects on diabetic retinopathy.

There has been an increase in the range of non-insulin anti-hyperglycaemic agents used to treat type 2 diabetes. With the globally rising rates of type 2 diabetes and complications such as diabetic retinopathy, it is important for ophthalmologists to be aware of these new agents and their impacts on diabetic retinopathy and diabetic macular oedema. We conducted a review of the literature to determine if there were any beneficial or harmful effects of the currently used anti-hyperglycaemic agents on diabetic retinopathy or diabetic macular oedema. Our review of the current literature found that apart from thiazolidinediones, anti-hyperglycaemic agents have been reported to have beneficial or neutral effects on diabetic eye complications. Thiazolidinediones (pioglitazone is the only one currently available) have been linked to incident or worsening diabetic macular oedema, although the rate is believed to be low. Glucagon-like peptide 1 (GLP1) agonists (incretins) in general are beneficial except semaglutide which is associated with increased rates of diabetic retinopathy complications. These results have implications for selection of anti-hyperglycaemic agents for patients with diabetic retinopathy or macular oedema. Further studies need to be conducted to identify if reported beneficial effects are independent of the impact of glycaemic control. Early worsening of retinopathy with tight glycaemic control should also be noted in interpretation of future studies.