ARAKI Eiichi Kumamoto University, Graduate School of Medical Sciences, Professor, 大学院・医学薬学研究部, 教授 (10253733)
MIYAMURA Nobuhiro Kumamoto University, Graduate School of Medical Sciences, Associate Professor, 大学院・医学薬学研究部, 講師 (40274716)
TOYONAGA Tetsushi Kumamoto University, Graduate School of Medical Sciences, Research Associate, 大学院・医学薬学研究部, 助手 (60295128)
|Budget Amount *help
¥3,500,000 (Direct Cost: ¥3,500,000)
Fiscal Year 2005: ¥1,700,000 (Direct Cost: ¥1,700,000)
Fiscal Year 2004: ¥1,800,000 (Direct Cost: ¥1,800,000)
An ultimate goal of the development of an artificial endocrine pancreas is to achieve long-term strict glucose regulation in diabetes patients. In 1982, Shichiri et al succeeded in miniaturizing the glucose monitoring system into needle-type glucose sensor, and then we developed a wearable artificial endocrine pancreas (WAEP) which consisted of a needle-type glucose sensor, a microcomputer system, and a insulin infusion pump.
In this study, in order to develop a new WAEP system for long-term clinical application in ambulatory diabetes patients, One problem should be solved ; It is the development of a reliable, stable and miniaturized glucose monitoring system,
Then, we developed a newly designed micro needle-type glucose sensor using flexible polyimide, named PI sensor (outer diameter, 0.3 mm ; length, 16 mm), and investigated its characteristics in vitro and in vivo.
Furthermore, by using this sensing system, we estimated the correlation and the time delay between subcutaneous tissue glucose concentrations and blood glucose concentrations. As a result, excellent characteristics of PI sensor were observed in vitro, and the correlation and the time delay between subcutaneous tissue (Y : mg/100ml) and blood glucose concentrations (X : 30-350 mg/100ml) was Y=1.03X+7.98 (r=0.969) and 6.6 ± 1.2 minutes, respectively.
Furthermore, to evaluate the feasibility of a new WAEP system consisted of a PI sensor for sensing system and new algorithm for control system, glucose control after oral glucose load of 1.5 g/kg was tried in diabetic dogs. By using this system, excellent glucose control (post-challenge blood glucose levels of 178.2 ± 19.3 mg/100ml at 75 min and 83.6 ± 11.8 mg/100ml at 240 min, respectively) could be achieved without any hypoglycemia (below 60 mg/100ml). Thus, by using a new WAEP system, it is expected that closed-loop insulin delivery system will be used widely in diabetes patients, and long-term perfect glucose control be achieved.