The development of wearable-type artificial endocrine pancreas and its usefulness in glycaemic control of human diabetes mellitus.

We have succeeded in miniaturizing a glucose monitoring system into a needle-type which preserves the characteristics suitable for application in a wearable closed-loop control system. The wearable artificial endocrine pancreas (12 X 15 X 6 cm, 400 g) consists of the sensor, a microcomputer which calculates the insulin and glucagon infusion rates and of a 2-syringe driving system. The device succeeded in controlling glycaemia perfectly in depancreatized dogs for a period of 3 days, and with replacement of subcutaneously inserted sensor for up to 7 days. When glucose monitoring by a needle-type glucose sensor inserted into subcutaneous tissue of the forearm or abdomen of healthy and diabetic volunteers was attempted, the readings were about 10% lower than blood glucose concentrations, but good correlation between them was observed in the range of 60 to 400 mg/dl. Perfect glycaemic control was established by infusing insulin either intravenously or subcutaneously in response to measured glucose concentrations on a moment-to-moment basis in diabetics for a period of several days. These results might indicate the feasibility of long-term glycaemic control in ambulatory diabetic patients with a wearable closed-loop glycaemic control system.