Skin Problems Common at Insulin Pump Infusion Sites

The study covered in this summary was published in The Lancet as a preprint and has not yet been peer reviewed.

Key Takeaways

  • Allergic sensitization at insulin pump sites is common.

  • Pump vs control sites had greater vessel density, fibrosis, fibrinogen, and inflammation including eosinophils, insulin-like-growth factor-1 (IGF-1), and transforming growth factor (TGF) β-3, as well as fat necrosis.

  • The tissue changes resulting from these skin responses could potentially lead to the infusion site failures commonly seen in clinical practice.

Why This Matters

  • Approximately 55% of diabetic ketoacidosis episodes in patients using insulin pumps are reportedly due to “pump/tubing” malfunctions.

  • Anecdotally, pump discontinuation is common after 20 years, owing to site failures, but just how frequently this occurs is unknown.

  • Little is understood about the cutaneous changes from chronic insulin infusion and how this may impact infusion site failure.

Study Design

  • Optical coherence tomography (OCT) was performed immediately before skin punch biopsy samples were collected at three sites: a “current site,” a “recovery site” ― used 3 days prior to biopsy ― and a “control” site never used for any insulin infusion or injection.

  • Analysis included 25 participants with a total of 75 skin sites.

  • Pump brands used were Medtronic, Tandem, and Omnipod, with steel, teflon, and Omnipod infusion sets used.

Key Results

  • Cutaneous symptoms at pump sites were common, with 93.3% of participants reporting itching and 76.7% reporting skin redness.

  • The OCT angiography microvascular maps showed increased blood vessels in both current and recovery pump sites vs control sites.

  • Statistical analysis showed a significant difference in vessel area density between pump and control sites (P < .0001) and between recovery and current pump sites (P < .001).

  • In histologic analysis, both current and recovery sites showed increased fibrosis, fibrinogen, inflammation, vascularity, and fat necrosis compared to control sites (all P < .001), with no significant differences seen between the current and recovery sites.

  • No eosinophils were observed in skin biopsy samples at the control sites, whereas eosinophils were identified in 73% of skin biopsy samples from the current sites (P < .01) and 75% of skin samples from the recovery sites (P < .01).

  • All study participants had eosinophils (range, 0–31/high power field; median, 4) identified in at least one current and/or recovery insulin infusion sites, located deep in the dermis near the interface with the fat.

  • There was no significant association between the type of insulin or pump brand and number of eosinophils.

  • Higher eosinophil counts were seen in patients using pumps for <10 years compared to those using pumps >20 years (P = .02).

  • Immunohistochemical staining also showed differences between current/recovery sites and the control site for insulin-like-growth factor-1 (IGF-1) and transforming growth factor β-3, but no difference with IGF1 receptor.

  • There were no differences in either OCT or histologic findings based on duration of pump use or with prior use of animal insulin.


  • The sample size was relatively small.

  • The cohort consisted of adults who were mostly White, with normal weight and with excellent glycemic control.

  • The findings may not be generalizable to other populations, particularly younger patients.


  • The study was funded by the Leona M. and Harry B. Helmsley Charitable Trust.

  • Lead author Kalus has no disclosures, but one author reports grants and/or consulting fees from various sources, including Insulet, Medtronic, Dexcom, Abbott Diabetes, Roche, Bigfoot, and Lifescan.

This is a summary of a preprint research study, “Evaluation of Insulin Pump Infusion Sites in Type 1 Diabetes,” by Andrea Kalus, MD, of the University of Washington School of Medicine, Seattle, and colleagues. This study has not yet been peer reviewed.

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