Endocrine Abstracts

Diabetic retinopathy remains the leading cause of blindness in the developed world resulting in significant morbidity for the diabetes population. As yet the specific pathogenesis remains elusive. Endogenous growth hormone (GH) is implicated in the development of retinal new vessels that characterize proliferative retinopathy. Both endogenous GH and its active protein, Insulin like growth factor-1 (IGF-1) have been found to be at high levels in diabetes, especially in patients with suboptimal glycaemic control.

The role of exogenous GH in both diabetic and non-diabetic retinopathy is less clear. Exogenous GH was first licensed for therapeutic use in 1996; there have subsequently been case reports of exogenous GH administration being associated with proliferative retinopathy in non-diabetic patients. However, there has also been reported a case series of 85 non-diabetic children on recombinant GH therapy who were screened prospectively for the development of proliferative retinopathy and were found to have none.

We present a case that supports the finding of proliferative retinopathy during recombinant GH therapy, albeit in this case a known diabetic patient. There are no previous case reports of worsening of stable background diabetic retinopathy during recombinant GH treatment.

On the contrary however, proliferative retinopathy was reported to have developed in a woman with pre-existing diabetes that subsequently developed GH deficiency but was never given GH replacement therapy.

In the current era of diabetes, new agents are overwhelming the therapeutic menu but limiting its use due to unforeseen outcomes. This is another therapeutic option which calls for caution in its prudent use until further studies demonstrating the role of GH and/or IGF1 in developing proliferative retinopathy are available.

We would therefore advise baseline and ongoing periodic screening for the development of new retinopathy in diabetic patients with coexistent GH deficiency, particularly those in whom treatment with recombinant GH is being instigated.