Whilst it is recognised that diabetic retinopathy is a consequence of prolonged elevation of blood glucose levels, recent studies suggest rapid normalisation of blood sugar as a causal factor in accelerating its development. In this case report, a non-insulin dependent diabetic with poor blood glucose control but no retinopathy in early pregnancy had normalisation of glucose control by the third trimester. However, glucose control deteriorated rapidly postnatally, and she had a sudden blurring of vision three months after delivery of her baby, at which time severe proliferative diabetic retinopathy was diagnosed. The reason for the unusually rapid development of proliferative retinopathy was uncertain, but appeared to have a temporal association with the deterioration of her glycaemic control postnatal after a period of strict diabetes control in the perinatal period.