Capillary Biomedical Inc. (CapBio) has developed an improved, kink-resistant, angled insulin infusion set (IIS) with a softer cannula material and 3 additional side holes for better insulin delivery. This study aimed to compare a regular 90° Teflon IIS (T90) with the CapBio improved IIS.
40 T90 and 48 CapBio IISs were inserted subcutaneously every other day for 2 weeks in 11 swine and connected to an insulin pump (basal/bolus pattern). After 2 weeks, the tissue surrounding the cannulas was excised and kinking within the tissue determined using micro-CT. The specimens were processed and stained with Masson’s Trichrome to assess the area of inflammation (AI) and thickness of inflammatory layer (LT) surrounding the cannula. Data were analyzed using Fisher’s Exact, ANOVA GLM, Kruskal Wallis, and post hoc Tukey HSD and Dwass-Steel-Chritchlow-Fligner tests.
AI and LT were consistently higher using T90, with statistically significant differences after 6 days of IIS wear time. On average, the AI was reduced by 52.6% and the LT by 66.3% using the angled CapBio IIS. While 32.5% (13/40) of T90 IISs kinked (=bend in cannula >90°), only 2.1% (1/47) of the CapBio IISs kinked (p<0.001).
The data suggest that the new cannula design of the CapBio IIS causes less tissue trauma compared to a regular 90° Teflon IIS between 2 days and 2 weeks post insertion and is resistant to kinking. These results are supportive of the objective of extending infusion set wear through changes to the material and mechanical design of traditional IIS cannulas.