Acromegaly is complicated by diabetes mellitus because of the action of growth hormone (GH) which induces the production of insulin-like growth factor I (IGF-I). IGF-I may contribute to the development of diabetic retinopathy in an autocrine and/or paracrine manner.1 In patients with acromegaly who demonstrate excessive secretion of GH, the incidence of retinopathy is reportedly very low and severe retinopathy is rare.2 3 This report describes a patient with severe proliferative diabetic retinopathy in both eyes associated with acromegaly. We performed pars plana vitrectomy and calculated the levels of angiogenic growth factors (IGF-I and vascular endothelial growth factor, VEGF) in the vitreous of both eyes to learn whether GH and/or IGF-I may influence the progression of diabetic retinopathy in proliferative diabetic retinopathy associated with acromegaly.4 5