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

Electrooxidation of Phenol on Polyelectrolyte Modified Carbon Electrodes for Use in Insulin Pump Infusion Sets

BACKGROUND

Many type 1 diabetes patients using continuous subcutaneous insulin infusion (CSII) suffer from the phenomenon of unexplained hypoglycemia or "site loss." Site loss is hypothesized to be caused by toxic excipients, for example, phenolic compounds within insulin formulations that are used as preservatives and stabilizers. Here, we develop a bioinspired polyelectrolyte-modified carbon electrode for effective electrooxidative removal of phenol from insulin and eventual incorporations into an infusion set of a CSII device.

METHODS

We modified a carbon screen printed electrode (SPE) with poly-L-lysine (PLL) to avoid passivation due to polyphenol deposition while still removing phenolic compounds from insulin injections. We characterized these electrodes using scanning electron microscopy (SEM) and electrochemical impedance spectroscopy (EIS) and compared their data with data from bare SPEs. Furthermore, we performed electrochemical measurements to determine the extent of passivation, and high-performance liquid chromatography (HPLC) measurements to confirm both the removal of phenol and the integrity of insulin after phenol removal.

RESULTS

Voltammetry measurements show that electrode passivation due to polyphenol deposition is reduced by a factor of 2X. HPLC measurements confirm a 10x greater removal of phenol by our modified electrodes relative to bare electrodes.

CONCLUSION

Using bioinspired polyelectrolytes to modify a carbon electrode surface aids in the electrooxidation of phenolic compounds from insulin and is a step toward integration within an infusion set for mitigating site loss.

Advances in Insulin Infusion Set in the New Era of Automated Insulin Delivery: A Systematic Review

INTRODUCTION

Automated insulin delivery (AID) has become a well-known research topic devoted to achieving better glycemic outcomes. AID systems consist primarily of three components: the continuous glucose monitoring system, the insulin delivery system, either tethered or patch pump, and the control system (algorithm). A key component in the tethered pump AID system is the insulin infusion set (IIS). This Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) study was conducted to evaluate the IIS evolution in the era of AID and to provide future perspectives of IIS clinical use.

METHODS

Literature searches for articles published from January 2016 to July 2022 were performed in Embase/Medline and PubMed. Data were extracted following PRISMA guidelines. Primary meta-analysis outcomes were IIS wear duration, total daily dose of insulin, and IIS failure reasons/modes.

RESULTS

We identified 387 publications, of which 15 eligible studies compared various IISs comprising over 1400 participants and >53 000 wears. Half of the studies published in 2022 were focused on extended IISs designed for wear durations of seven days or more. Three clinical trials have demonstrated the safe use of extended IISs to seven days of wear in individuals with type 1 diabetes, and two also demonstrated good glycemic control throughout the seven-day use.

CONCLUSIONS

Research in insulin infusion technology has increased in the last six years, and extended IISs have demonstrated improved overall performance, particularly in duration of wear. Paths for future products are discussed with an emphasis on understanding the existing barriers related to both technical and nontechnical issues.

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).

Closed-loop insulin delivery: update on the state of the field and emerging technologies

INTRODUCTION

Over the last five years, closed-loop insulin delivery systems have transitioned from research-only to real-life use. A number of systems have been commercialized and are increasingly used in clinical practice. Given the rapidity of new developments in the field, understanding the capabilities and key similarities and differences of current systems can be challenging. This review aims to provide an update on the state of the field of closed-loop insulin delivery systems, including emerging technologies.

AREAS COVERED

We summarize key clinical safety and efficacy evidence of commercial and emerging insulin-only hybrid closed-loop systems for type 1 diabetes. A literature search was conducted and clinical trials using closed-loop systems during free-living conditions were identified to report on safety and efficacy data. We comment on emerging technologies and adjuncts for closed-loop systems, as well as non-technological priorities in closed-loop insulin delivery.

EXPERT OPINION

Commercial hybrid closed-loop insulin delivery systems are efficacious, consistently improving glycemic control when compared to standard therapy. Challenges remain in widespread adoption due to clinical inertia and the lack of resources to embrace technological developments by health care professionals.