In diabetic patients in Japan, gangrene, and ulcers of the lower extremities were found in 2% of out-patients and in 4% of hospitalized patients. This prevalence in Japan is much less than in Western countries, as already shown by the Multinational Study on Vascular Diabetic Diseases. The ratio of ulcers due to neuropathy is 3 or 4 times more than that caused by ASO. But recent trends showed a gradual increase in ASO among diabetic patients. According to the API measured by the ultrasonic Doppler method, the prevalence of ASO is estimated as being 10% of diabetic patients, and about one tenth of ASO patients will develop gangrene in future.