Chlorpropamide alcohol flushing and diabetic retinopathy.

"Mason-type" diabetics (mild diabetes which is dominantly inherited) are relatively free of retinopathy. Alcohol almost invariably causes facial flushing in these patients when they are given chlorpropamide (chlorpropamide alcohol flush, C.P.A.F.). 291 non-insulin-dependent diabetics were examined to see whether there was a difference in frequency of retinopathy between C.P.A.F. positive and negative cases who were of comparable age and duration of diabetes. Retinopathy was commoner and often severe in CPAF negative patients. Blindness from retinopathy was almost confined to C.P.A.F.-negative cases. Lens opacities, on the other hand, were equally common in both groups. Since C.P.A.F. is an inherited trait, retinopathy in non-insulin-dependent diabetics is to a considerable extent, although not entirely, determined by genetic factors.