BACKGROUND Diabetic dermopathy is the most common specific cutaneous finding in diabetes. OBJECTIVE Using laser Doppler technology, we tested the hypothesis that diabetic dermopathy arises from abnormal local skin blood flow. METHODS We measured cutaneous blood flow in patients with type 1 diabetes without dermopathy and compared values with those in a control group of patients with type 1 diabetes without diabetic dermopathy and in a nondiabetic group. We measured at 3 separate sites on the pretibial area on the legs of each participant, at dermopathy lesions, and at a number of standard sites on the upper and lower extremities. RESULTS We studied 25 patients with diabetes and diabetic dermopathy, average age 51 ± 2 years, mean duration of diabetes 28 ± 3 years. In all, 58 patients with type 1 diabetes without diabetic dermopathy served as control patients, average age 41 ± 2 years, mean duration of diabetes 23 ± 2 years. There were 67 nondiabetic control subjects, average age 47 ± 3 years. The patients with diabetic dermopathy showed a marked reduction in skin blood flow at 35°C at normal-appearing skin areas on the pretibial surface of the legs (1.1 ± 0.1 mL/min/100 g) compared with 1.7 ± 0.1 mL/min/100 g (P = .01) in the type 1 diabetic control group and 2.1 ± 0.3 mL/min/100 g (P < .01) in the nondiabetic group. The dermopathy lesions themselves showed markedly higher blood flow: 2.5 ± 0.3 mL/min/100 g. CONCLUSIONS Our diabetic dermopathy patients were somewhat older than the control type 1 diabetes subjects, but were of comparable age to the nondiabetic subjects. CONCLUSIONS These results suggest that patients susceptible to diabetic dermopathy have a functional abnormality in blood flow leading to this scarring process.