Computer-aided continuous drug infusion: setup and test of a mobile closed-loop system for the continuous automated infusion of insulin

Abstract

For a diabetes mellitus patient, tight control of glucose level is essential. Results are reported of an investigation of the suitability of existing wearable continuous insulin infusors controlled and adjusted by a control algorithm using continuous glucose measurements as input to perform the functionality of an artificial pancreas. Special attention was given to the development of a continuous glucose monitor and to evaluate which quality of input data is necessary for the control algorithm. In clinical trials, it was found that for patients in a controlled environment an autonomously regulating control algorithm leads to an improved adjustment of patient glucose values and less overall insulin infusion as compared with the best fixed preprogrammed insulin infusion profiles of standard pump therapy. For the limited number of cases studied here, functionality of the control algorithm could tolerate some delay between the actual glucose values in the patient interstitial fluid and the algorithm input of up to 30 min. A quasicontinuous glucose measurement delivering actual glucose values every 5-10 min seems to be suited to control an artificial pancreas.

A Survey of Insulin-Dependent Diabetes—Part I: Therapies and Devices

“…However, in practice, many parameters around the metabolism, such as environmental conditions, stress of patients, behavioral changes, and duration of tests make a calculation of the actual demand of exogenous insulin intricate [23]. As a result, designed algorithms and mathematical representations must be complex and nonlinearly modeled in order to resemble the real hormone secretion [24]. …”

“…The in vivo glucose sensors typically are implanted subcutaneously and send blood glucose profiles as vital signals to exterior receivers, such as PDAs or laptop PCs, at very short intervals. Since many samples make modeling a blood glucose curve relatively easy resulting in enhancing predictions of the future transition of blood glucose concentration [24], the in vivo sensors are considered to be largely beneficial to a reliable insulin-dependent diabetes therapy. Currently in collaboration with an insulin pump, in vivo blood glucose sensors are integrated into closed-loop blood glucose control systems.…”

“…Currently, only three-day monitoring is considered to be safe and reliable [24, 26]. In addition, these blood glucose sensors largely still rely on the discrete measurements rather than continuous ones [24]. …”

“…One type of these implantable sensors is needle-type sensors [24]. These needle-type sensors are intravenously or subcutaneously inserted into the body.…”

The INCA System: A Further Step Towards a Telemedical Artificial Pancreas

“…The dream of an "artificial pancreas" is starting to become reality [9], [10], supported by the increased availability of continuous glucose monitoring solutions, the integration of control systems capable of closing the loop by modifying the pump parameters, and the development of portable devices with capabilities to manage the former technologies [11]. One of the most advanced solutions to achieve an SC-SC closed-loop control system has been developed within the research project "advanced insulin infusion using a control loop" (ADICOL) [12] that developed a novel nonlinear model predictive glucose controller, running on a portable hand-held device to administer automatically a precise insulin dosage using the information provided by the glucose sensor.…”