Continuous subcutaneous insulin infusion (CSII) for type 1 diabetes is increasing in use. Pump site failures are common, but little is known about skin changes from pump use. Using noninvasive optical coherence tomography (OCT), OCT angiography (OCTA), and skin biopsies, we evaluated skin changes from chronic insulin infusion.


In this cross-sectional study, OCT operating at a 1,310-nm central wavelength with a bandwidth of 100 nm was performed immediately before skin punch biopsies were collected at three sites: the current site, with the infusion set removed at time of OCT and biopsy; the recovery site, with the infusion set removed 3 days before biopsy; and the control site, which was never used for any insulin infusion or injection.


OCT and OCTA identified characteristics of increased inflammation and vessel density at pump sites compared with control sites. Histologic analysis of pump sites showed differences in skin architecture, including fibrosis, inflammation (including increased tissue eosinophils), and fat necrosis. Immunohistochemical staining showed differences between infusion and control sites regarding staining of ILGF-I and transforming growth factor-β3.


These findings support allergic sensitization as a potentially common reaction at CSII sites. The leading candidates causing this include insulin preservatives, plastic materials, and adhesive glue used in device manufacturing. The inflammatory response caused by these common allergic responses may result in tissue changes responsible for the infusion site failures seen frequently in clinical practice.

This article contains supplementary material online at https://doi.org/10.2337/figshare.23519205.

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