Two bedside-type artificial endocrine pancreases, the Biostator® from Miles Labratory, Ltd., U. S. A. and the STG-22® from Nikkiso Co., Ltd, Japan, are now widely applied to diabetic patients in Japan. The Artificial Organs Registry in Japan shows that clinical application of this bedside-type artificial endocrine pancreas has been increasing with time: the cumulative number of cases applied from 1983 to 1991 was more than 4726, and the number of cases applied in 1991 was 1044. Among these, application of this system for quantitative determination of insulin sensitivity is increasing greatly these days. Claims of mechanical failure, such as electrical, computer and sensing failure, have been reported in less than 1% of applications. Thus, it has been established that the bedside-type artificial endocrine pancreas is useful not only as a therapeutic tool for diabetes mellitus, but also as an elegant research tool for investigating the pathophysiology of the disease. Although minor improvements or modifications have been suggested diabetologists as well as diabetic patients are waiting for the development and clinical application of a wearable artificial endocrine pancreas that will accomplish strict long-term glycemic control in diabetic patients.