- A history of major microvascular disease defined as any one of nephropathy (albumin:creatinine ratio >300ug/mg), retinal photocoagulation therapy, proliferative retinopathy (new blood vessels on the disc or elsewhere, vitreous haemorrhage, pre-retinal haemorrhage, or fibrous proliferations on the disc or elsewhere), macular oedema (retinal thickening within one disc diameter of the macular centre) or blindness in either eye (corrected visual acuity 6/60 or worse, persisting for three months or more) not known to be due to non-diabetic causes or