For generations it has been taught that myopic change is the principal response to hyperglycaemia in diabetes mellitus. Recently, however, a hyperopic concept has been advanced, to suggest that a change towards hypermetropia has possibly become the more frequent finding in diabetics with unstable refraction. The present sample comprises 32 cases of newly discovered diabetes and 40 cases of long duration, most cases being insulin-dependent. Of the former 47% showed a refractive change around the recognized onset of diabetes, in some cases prior to detection and admission, but mostly after institution of insulin therapy; in 14/15 the change was towards hypermetropia. Of the longstanding cases 20% showed refractive change (while 80% did not) in association with poor metabolic control, equally towards myopia/hypermetropia. It was not possible to point out an association with specific patterns of metabolic dysregulation. The results are further discussed in relation to previous refraction studies demonstrating an increased myopia prevalence in diabetics in general, as compared to non-diabetics. Apparently this cannot be explained merely by a possibly overlooked transient refractive change under periods of poor metabolic control.