The diabetes medication Avandia (rosiglitazone maleate, GlaxoSmithKline) may delay the onset of proliferative diabetic retinopathy (PDR), according to a study published in the June issue of Archives of Ophthalmology. The anti-angiogenic properties of rosiglitazone may slow retinal neovascularization caused by PDR, according to the authors of the study. But, should it be used for this purpose?

The one-year study compared the eyes of 124 patients with diabetes, who were treated with oral rosiglitazone, to the eyes of 158 non-treated patients with diabetes. After initial analysis, the researchers determined that 14 eyes in the rosiglitazone group and 24 eyes in the control group demonstrated severe nonproliferative diabetic retinopathy. At the three-year follow-up examination, 19.2% of eyes in the rosiglitazone group progressed to PDR, compared with 47.4% of eyes in the control group.

The researchers concluded that nonproliferative diabetic retinopathy patients in the rosiglitazone group had a 59.5% relative risk reduction for PDR development.

Though the results seem promising, this study might have a few problems. Most importantly, patients in the rosiglitazone group were much less likely to be on insulin therapy than the control group. Insulin use (and concomitant expression of insulin-like growth factor) is associated with up-regulation of vascular endothelial growth factora critical component in the development of PDR, says A. Paul Chous, O.D., M.A., who practices in Maple Valley, Wash., with special emphasis on diabetic eye disease and diabetes education. So, it may be that patients in the control group had more worsening of their diabetic retinopathy, at least partially, as a function of more insulin use.

Furthermore, While Avandia does appear to have anti-angiogenic properties in animal models it is definitely associated with a higher risk of peripheral edema and congestive heart failure, and may be associated with increased risk of myocardial infarction and death. Therefore, I am doubtful that Avandia will become widely used for preventing PDR, says Dr. Chous.

Shen LQ, Child A, Weber GM, et al. Rosiglitazone and delayed onset of proliferative diabetic retinopathy. Arch Ophthalmol 2008 Jun;126(6):793-9.

Vol. No: 145:07Issue: 7/15/2008