New insights into the pathogenesis of diabetic retinopathy--hormonal rather than metabolic factors are important.

Diabetic retinopathy has traditionally been viewed as a metabolite-driven, occlusive vasculopathy that affects both retinal microvascular haemodynamics and stricture; analogies to cholesterol-driven occlusive atherosclerosis of the macrovascular circulation were drawn. However this paradigm may no longer be appropriate. Recent evidence suggests that diabetic retinopathy from the beginning is the consequence of a complex hormonal dysfunction, which is related to insulin-dependent up- and downregulation of growth factors, to which metabolic, haemodynamic, endocrine, paracrine, and autocrine mechanisms contribute.