Combining Glucose Monitoring and Insulin Infusion in an Integrated Device: A Narrative Review of Challenges and Proposed Solutions

Abstract

The introduction of automated insulin delivery (AID) systems has enabled increasing numbers of individuals with type 1 diabetes (T1D) to improve their glycemic control largely. However, use of AID systems is limited due to their complexity and costs associated. The user must wear both a continuously monitoring glucose system and an insulin infusion pump. The glucose sensor and the insulin catheter must be inserted at two different body sites using different insertion devices. In addition, the user must pair and manage the different systems. These communicate with the AID software implemented on the pump or on a third device such as a dedicated display device or smart phone application. These components might be developed and commercialized by different manufacturers, which in turn can cause difficulties for patients seeking technical support. A possible solution to these challenges would be to integrate the glucose sensor and insulin catheter into a single device. This would allow the glucose sensor and insulin catheter to be inserted simultaneously, eliminating the need for pairing, and simplifying system management. In recent years, different technologies have been developed and evaluated in clinical investigations that combine the glucose sensor and the insulin catheter in one platform. The consistent finding of all these studies is that integration has no adverse effect on insulin infusion and glucose measurements provided that certain conditions are met. In this review, we discuss the perceived challenges of such an approach and discuss possible solutions that have been proposed.

Keywords: accuracy; automated insulin delivery; colocalization; continuous glucose monitoring; insulin delivery; integration.

Figure 1.

Schematic drawing of single- and dual-port integrated devices. (a) single-port device; (b) dual-port device; a, integrated body-worn device; b, dermis; c, subcutaneous tissue; d, glucose sensor with glucose sensitive tip (red); e, insulin catheter.

Figure 2.

The results of all 10 subjects are displayed. The continuous line represents the blood glucose values, the dotted line represents the control sensor, and the long dashed line represents the test sensor. The time of breakfast is indicated by the arrow. Source: Reproduced from Hermanides et al.

Figure 3.

Comparison of plasma and ISF-derived glucose concentrations observed during an overnight fast and oral gucose tolerance test (OGTT) in subjects with diabetes. (a) Average time course (n = 10, means ± SE) of plasma glucose concentration (•) and the tissue glucose concentration obtained with the microperfusion (MP) catheter used for insulin delivery and simultaneous glucose sampling (MP_I, □). A also shows the average time course (n = 10, means ± SE) of the insulin delivery rate (bars) used to control glucose concentration during experiments. (b and c) Average time course (n = 10, means ± SE) plasma glucose (•) and the tissue glucose obtained with the mannitol-perfused microperfusion catheters (MP_M1 and MP_M2, □). Abbreviation: ISF, interstitial fluid. Source: Reproduced from Lindpointner et al.

Figure 4.

(a) Combo-Set sensor versus (b) control Sof-Sensor glucose tracings. Abbreviations: BG, blood glucose; MBG, blood glucose measurement with a meter; SGV, sensor glucose value; CBG, meter blood glucose meter reading used for calibration. Source: Reproduced from O’Neal et al.