In Vivo Study of the Inflammatory Tissue Response Surrounding a Novel Extended-Wear Kink-Resistant Insulin Infusion Set Prototype Compared With a Commercial Control Over Two Weeks of Wear Time

Abstract

Background: Infusion set function remains the limiting factor of insulin pump therapy due to nonmetabolic complications. Here, we tested an investigational extended-wear infusion set prototype with a soft, angled, wire-reinforced cannula with three additional side holes, and compared failure mechanisms and tissue response with a commercial Teflon control. Methods: A total of 48 Teflon and 48 prototype infusion sets were inserted subcutaneously every other day for 14 days in 12 swine and infused with dilute insulin. After two weeks, tissue around cannulas was excised, and occlusions, leaks, and kinks were determined. Tissue was processed and stained to assess the total area of inflammation (TAI) and the inflammatory layer thickness (ILT) around the cannulas. Data were analyzed using Fisher’s exact, analysis of variance-general linear model, Kruskal-Wallis, and post hoc tests. Results: On average, the TAI surrounding the investigational cannula was 52.6% smaller than around the commercial control. The ILT was 66.3% smaller around investigational cannulas. Kinks occurred in 2.1% (investigational) vs 32.4% (commercial) cannulas ( P < .001). There was no difference in occlusion alarms and leaks onto skin. Conclusions: The data suggest that the infusion set prototype elicits less inflammation over an extended wear time and is resistant to kinking, compared with a commercial Teflon device. This is consistent with previously published data on the impact of cannula material/angle on the inflammatory tissue response. We highlight the following important aspects of infusion set design: (1) secure skin adhesion, (2) reliable cannula insertion, (3) automatic removal of the stylet, (4) cannula material/design that resists kinking, and (5) minimization of local tissue inflammation.

Impact of Infusion Set Materials and Designs on the Subcutaneous Response in People With Diabetes: A Rapid Review of the Literature

“…Investigations in swine have shown that angled infusion sets at 35° may result in less-severe inflammatory reactions than perpendicular sets. 53,54 Reports show that Teflon may result in less inflammation than steel in swine 55,56 although an earlier study reported minimal differences in keeping with data reported in humans. 57 A metaanalysis of such results warrants a dedicated systematic review.…”

Feasibility study of a prototype extended‐wear insulin infusion set in adults with type 1 diabetes

“…The prototype investigational Capillary Biomedical (Irvine, CA, USA) extended‐wear IIS (CBX IIS) contains a coil‐reinforced soft polymer (nylon‐derivative) indwelling cannula with one distal and three proximal ports (Figure 1A). This novel cannula has shown significantly improved immunological tolerability in pre‐clinical swine studies 16 . Each infusion set has two basic components: the infusion set body with an indwelling, angled cannula, and a tubing connector to the infusion pump reservoir (Figure 1B).…”

Lipohypertrophy and Insulin: An Update From the Diabetes Technology Society

“…Novel seven-day infusion sets may lead to fewer cases of LH, but studies are underway to quantify this hypothesis. 26,27 Additives in different types of insulin may also have some influence because of the introduction of foreign bodies that can activate the immune system. Insulin delivery via jet injectors has been speculated to decrease LH risk.…”