Survival assessment of the extended-wear insulin infusion set featuring lantern technology in adults with type 1 diabetes by the glucose clamp technique

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

Insulin infusion sets (IISs) are an integral and intricate part of continuous subcutaneous insulin infusion for subjects with type 1 diabetes, infusing insulin from pump to the subcutaneous space. Insulin infusion sets interface with the skin surface, the dermis, and the subcutaneous space and may be the cause of infusion failure due to biological events or mechanical problems. Novel IISs with extended wear time and anti-inflammatory properties to mitigate these issues are described in the literature although material-tissue interactions are poorly understood. This rapid review focuses on the impact of IIS materials and designs on the subcutaneous response in people with diabetes and includes literature identified in PubMed, Embase, and Cochrane databases. Twenty-one studies were identified for qualitative synthesis that encompassed a limited and heterogenic body of evidence including 10 clinical reports, six reviews, one case report, two abstracts, and two communications. Two clinical reports were randomized crossover studies. Reports on materials mostly compared steel versus polytetrafluoroethylene (Teflon) cannulas and suggested no substantial difference in tissue response to these materials. Reports on designs focused mostly on the angle of cannula insertion. To drive and improve research on extended wear and nonimmunogenic IISs, future studies should focus on material-tissue interaction as dedicated outcome measures, quantified with punch biopsy and imaging techniques such as ultrasound, optical coherence tomography, and confocal reflectance microscopy. Original studies are required to further a field too young for a systematic meta-analysis.

Evaluation of Insulin Lispro Pharmacokinetics and Pharmacodynamics Over 10 Days of Continuous Insulin Infusion in People With Type 1 Diabetes

BACKGROUND

We evaluated the effect of meloxicam on insulin lispro pharmacokinetics and glucose pharmacodynamics over 10 days of continuous subcutaneous insulin infusion (CSII) at one infusion site in people with type 1 diabetes (T1D).

METHOD

This phase 1, randomized, double-blind, single-center, two-way crossover study enrolled adults with T1D for ≥1 year on stable CSII for ≥3 months. Participants randomly received U100 insulin lispro and LY900027 (U100 insulin lispro + 0.25 mg/mL meloxicam). Primary end points were area under the insulin lispro curve from 0 to 5 hours (AUCIns.0-5h) after bolus administration prior to a mixed-meal tolerance test (MMTT) and maximum observed concentration of insulin lispro (CIns.max) on days 5, 7, and 10, versus day 3 (baseline).

RESULTS

A total of 20 participants were randomized. Insulin absorption was accelerated for insulin lispro and LY900027 from days 1 to 7. The AUCIns.0-5h was significantly lower on day 10 versus day 3 for LY900027 (-19%) and insulin lispro (-14%); the AUCIns.0-5h did not differ significantly between treatments. The CIns.max increased with LY900027 and insulin lispro (by ~14%-23% and ~16%-51%) on days 5, 7, and 10 versus day 3. The CIns.max of LY900027 was ~14%-23% lower than insulin lispro CIns.max on days 7 and 10 (P ≤ .0805). Accelerated insulin absorption and a modest loss of total insulin exposure led to a loss of MMTT glycemic control at later time points.

CONCLUSIONS

The pharmacokinetics of insulin changed over catheter wear time even when an anti-inflammatory agent was present. Postprandial glycemic control was adversely affected by the accelerated insulin absorption and decreased insulin exposure.

Progressive Acceleration of Insulin Exposure Over 7 Days of Infusion Set Wear

Insulin exposure varies over 3 days of insulin infusion set (IIS) wear making day-to-day insulin dosing challenging for people with diabetes (PWD). Here we report insulin pharmacodynamic (PD) and pharmacokinetic (PK) data extending these observations to 7 days of IIS wear. PWD (A1C ≤8.5%, C-peptide <0.6 nmol/L, ≥6 months pump use) were enrolled in a crossover euglycemic clamp pilot study comparing conventional Teflon angled IISs with an investigational extended-wear IIS. PK/PD data from six participants were obtained for 5 h postbolus. Although PD data were unstable, PK profiles (pooled data from both groups) of insulin lispro (0.15 U/kg bolus) showed statistically significant progressive decreases from days 0 to 7 for t_max (P < 0.001), C_max (P < 0.05), and mean residence time (P < 0.0001). Area under the insulin concentration curve (AUC_0-300) declined by ∼24% from days 0 to 7 (P < 0.05). These results confirm/extend previous observations showing progressive acceleration of insulin exposure over IIS wear time. This may have implications for PWD and designers of closed-loop algorithms, although larger studies are necessary to confirm this. The study was registered in clinicaltrials.gov (NCT04398030).

Insulin Derived Fibrils Induce Cytotoxicity in vitro and Trigger Inflammation in Murine Models

BACKGROUND

Effective exogenous insulin delivery is the cornerstone of insulin dependent diabetes mellitus management. Recent literature indicates that commercial insulin-induced tissue reaction and cellular cytotoxicity may contribute to variability in blood glucose as well as permanent loss of injection or infusion site architecture and function. It is well accepted that insulin formulations are susceptible to mechanical and chemical stresses that lead to insulin fibril formation. This study aims to characterize in vitro and in vivo toxicity, as well as pro-inflammatory activity of insulin fibrils.

METHOD

In vitro cell culture evaluated cytotoxicity and fibril uptake by macrophages and our modified murine air-pouch model quantified inflammatory activity. The latter employed FLOW cytometry and histopathology to characterize fibril-induced inflammation in vivo, which included fibril uptake by inflammatory phagocytes.

RESULTS

These studies demonstrated that insulin derived fibrils are cytotoxic to cells in vitro. Furthermore, inflammation is induced in the murine air-pouch model in vivo and in response, macrophages uptake fibrils both in vitro and in vivo.

CONCLUSIONS

Administration of insulin fibrils can lead to cytotoxicity in macrophages. In vivo data demonstrate insulin fibrils to be pro-inflammatory which over time can lead to cumulative cell/tissue toxicity, inflammation, and destructive wound healing. Long term, these tissue reactions could contribute to loss of insulin injection site architecture and function.

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

AIM

To assess the feasibility of a prototype insulin infusion set (IIS) for extended wear in adults with type 1 diabetes.

MATERIALS AND METHODS

The prototype Capillary Biomedical investigational extended-wear IIS (CBX IIS) incorporates a soft, flexible, reinforced kink-resistant angled nylon-derivative cannula with one distal and three proximal ports to optimize insulin delivery. Twenty adult participants with type 1 diabetes established on insulin pump therapy used the CBX IIS for two 7-day test periods while wearing a Dexcom G5 continuous glucose monitor.

RESULTS

Participants were able to wear the CBX IIS for an average of 6.6 ± 1.4 days. Eighty-eight percent (36 of 41) of sets were worn for 7 days. No serious adverse events were reported. Five infusion sets failed prematurely because of: unresolvable hyperglycaemia (three); hyperglycaemia with elevated ketones (one); or infection (one). Median time in range (3.9-10.0 mmol/L) was 62% (54-76). Average glucose levels per day of infusion set wear showed a statistically significant increase over time (p < .001).

CONCLUSIONS

Our preliminary observations confirm the tolerability of the prototype CBX IIS for extended wear, albeit with a deterioration in glucose control after the third day.

Improving the Patient Experience With Longer Wear Infusion Sets Symposium Report

Continuous subcutaneous insulin infusion (CSII) therapy is becoming increasingly popular. CSII provides convenient insulin delivery, precise dosing, easy adjustments for physical activity, stress, or illness, and integration with continuous glucose monitors in hybrid or other closed-loop systems. However, even as insulin pump hardware and software have advanced, technology for insulin infusion sets (IISs) has stayed relatively stagnant over time and is often referred to as the "Achilles heel" of CSII. To discuss barriers to insulin pump therapy and present information about advancements in, and results from clinical trials of extended wear IISs, Diabetes Technology Society virtually hosted the "Improving the Patient Experience with Longer Wear Infusion Sets Symposium" on December 1, 2021. The symposium featured experts in the field of IISs, including representatives from Steno Diabetes Center Copenhagen, University of California San Francisco, Stanford University, Medtronic Diabetes, and Science Consulting in Diabetes. The webinar's seven speakers covered (1) advancements in insulin pump therapy, (2) efficacy of longer wear infusion sets, and (3) innovations to reduce plastics and insulin waste.

Survival assessment of the extended-wear insulin infusion set featuring lantern technology in adults with type 1 diabetes by the glucose clamp technique

Maintaining good glycaemic control with the same infusion set for longer than 3 days may improve the quality of life of insulin pump users. The aim of the current study was to assess the efficacy and safety of the novel, extended-wear infusion set over 7 days of wear in adults with type 1 diabetes. Sixteen participants completed three identical 8-hour euglycaemic clamp experiments on Days 1, 4 and 7 of infusion set wear. Between the experiments, the participants were discharged home for routine diabetes management while wearing the same extended-wear infusion set throughout the study. Time to reach the maximum glucose infusion rate (T_GIRmax ) on Day 7 was reduced by 67% compared with Day 1 (p < .001). The corresponding area under the glucose infusion rate curve (AUC_GIR ) was comparable for the first 2 h of the clamp (p = .891) but decreased by 28% over time (p < .008). While the extent of insulin absorption decreased with prolonged wear, it was accompanied by an increase in insulin absorption rate. The infusion set survival rate was 100% without leakages, occlusion alarms, severe hypoglycaemia or ketoacidosis. The extended-wear infusion set proved safe and effective during prolonged wear in real-life conditions.

The improved survival rate and cost-effectiveness of a 7-day continuous subcutaneous insulin infusion set

AIMS

The purpose of this article is to compare the insulin cost-savings of the Medtronic Extended Infusion Set (or EIS, a.k.a. Extended Wear Infusion Set) designed and labeled for up to 7-day use with rapid-acting insulins to the current standard of care, 2- to 3-day infusion sets.

METHODS

There are three major improvements (reducing insulin waste, plastic waste, and adverse events) with the extended duration of infusion set wear. This analysis focuses on cost savings from reduced insulin wastage during set changes. Studies published on insulin infusion set survival and EIS clinical trial data (NCT04113694) were used to estimate device lifetime performance using a Markov chain Monte Carlo model, including the assessment of adverse effects and device failure. Total costs associated with infusion set change or failure were systematically found in published literature or estimated based on physical usage, and the direct impact on insulin costs was calculated.

RESULTS

Based on the model and clinical data, EIS users can expect to change their infusion sets about 75 fewer times than standard set users each year. The costs related to unrecoverable insulin during an infusion set and reservoir change in the US were estimated to range from $19.79 to $22.48, resulting in approximately $1324 to $1677 in annual cost-savings for the typical user from minimizing insulin wastage.

LIMITATIONS

The study only assessed devices used within a monitored setting, that is, clinical trials. In addition, the variability associated with healthcare standards and costs and individual treatment variability including insulin dosages, contribute to the uncertainties with the calculations.

CONCLUSIONS

Our analysis demonstrates that by extending the duration of infusion set wear, there may be substantial cost savings by reducing insulin wastage.