Seventy patients with non-insulin dependent diabetes (NIDD) were studied for the chlorpropamide-alcohol flush (CPAF), first degree family history of diabetes, macroangiopathy and for peripheral neuropathy. Positive CPAF challenge tests were found in 65% of the tested subjects and in 77% if there was a family history of diabetes. Signs of macroangiopathy (loss of foot pulses) were significantly (p less than 0.05) less common in the CPAF positive than in the CPAF negative diabetics with a duration of diabetes of ten years or less. With a longer duration this difference between the two groups was reduced. Also signs of peripheral neuropathy (abnormal vibration sense) were less common (p less than 0.05) in the CPAF positive diabetics than in the CPAF negative. Previously a low prevalence of retinopathy in teh CPAF positive non-insulin dependent diabetics has been reported. We have shown that this is also true of peripheral macroangiopathy and peripheral neuropathy. Chlorpropamide-alcohol flushing seems to be related to a relative protection against late complications in diabetes and the test might be used to find patients at risk.