Tissue Response to Subcutaneous Infusion Catheter

The DERMIS Study: Methodologies, Results, and Implications for the Future

Ongoing innovation in diabetes technologies has led to the development of advanced tools such as automated insulin delivery (AID) systems that adjust insulin delivery in response to current and predicted glucose levels, residual insulin action, and other inputs (eg, meal and exercise announcements). However, infusion sets continue to be the "Achilles heel" of accurate and precise insulin delivery and continued device use. A recent study by Kalus et al (DERMIS Study) revealed higher vessel density and signals of inflammation by optical coherence tomography (OCT), in addition to increased inflammation, fat necrosis, fibrosis, and eosinophilic infiltration by histopathology. Although the study provided a comprehensive description of what was happening, the results raise important questions that require additional research. On February 29, 2024, the Leona M. and Harry B. Helmsley Charitable Trust sponsored a conference to begin addressing these issues. This article summarizes the DERMIS study findings and testing methodologies discussed at the conference and proposes the next steps for developing insulin infusion sets that reduce the variability in insulin delivery and extend wear.

Promising strategies for smart insulin delivery system: Glucose-sensitive microneedle

The diabetes treatment landscape is rapidly evolving towards intelligent and precise therapeutic interventions. Among these advancements, glucose-sensitive microneedle patches (GSMPs), which can automatically adjust the transdermal release rate of insulin based on glucose concentrations, are emerging as a promising strategy. In this work, a new classification method has been proposed for GSMPs, categorizing them into integrated, all-in-one, and core-shell structures. The working mechanism and performance of GSMPs are thoroughly analyzed to compare the advantages and disadvantages of these three forms. The correlation between glucose-sensitive performance and normal blood glucose maintenance time (NGT) is further explored. Our findings indicate that all-in-one GSMPs demonstrate a positive correlation between in vitro glucose-sensitive controlled-release performance and NGT, unlike assembled GSMPs, where the performance is influenced by the matrix material and crosslinking factors. Simultaneously, challenges in clinical translation and future development trends are discussed from a patient's perspective. In summary, the new classification method, in-depth explanation of mechanisms, and analysis of challenges in this work contribute to a better understanding of the field of GSMPs and provide guidance for the development of more advanced and efficient GSMPs.

Development of a Real-time Force-based Algorithm for Infusion Failure Detection

BACKGROUND

Continuous subcutaneous insulin infusion (CSII) is a common treatment option for people with diabetes (PWD), but insulin infusion failures pose a significant challenge, leading to hyperglycemia, diabetes burnout, and increased hospitalizations. Current CSII pumps' occlusion alarm systems are limited in detecting infusion failures; therefore, a more effective detection method is needed.

METHODS

We conducted five preclinical animal studies to collect data on infusion failures, utilizing both insulin and non-insulin boluses. Data were captured using in-line pressure and flow rate sensors, with additional force data from CSII pumps' onboard sensors in one study. A novel classifier model was developed using this dataset, aimed at detecting different types of infusion failures through direct utilization of force sensor data. Performance was compared against various occlusion alarm thresholds from commercially available CSII pumps.

RESULTS

The testing dataset included 251 boluses. The Bagging classifier model showed the highest performance metrics among the models tested, exhibiting high accuracy (96%), sensitivity (94%), and specificity (98%), with lower false-positive and false-negative rate compared with traditional occlusion alarm pressure thresholds.

CONCLUSIONS

Our study developed a novel non-threshold classifier that outperforms current occlusion alarm systems in CSII pumps in detecting infusion failures. This advancement has the potential to reduce the risk of hyperglycemia and hospitalizations due to undetected infusion failures, offering a more reliable and effective CSII therapy for PWD. Further studies involving human participants are recommended to validate these findings and assess the classifier's performance in a real-world setting.

An injectable and biodegradable zwitterionic gel for extending the longevity and performance of insulin infusion catheters

Continuous subcutaneous insulin infusion (CSII) is an essential insulin replacement therapy in the management of diabetes. However, the longevity of clinical CSII is limited by skin complications, by impaired insulin absorption and by occlusions associated with the subcutaneous insertion of CSII catheters, which require replacement and rotation of the insertion site every few days. Here we show that a biodegradable zwitterionic gel covering the tip end of commercial off-the-shelf CSII catheters fully resolves early skin irritations, extends the longevity of catheters and improves the rate of insulin absorption (also with respect to conventional syringe-based subcutaneous injection) for longer than 6 months in diabetic mice, and by 11 days in diabetic minipigs (from 2 to 13 days, under standard CSII-wearing conditions of insulin pump therapy and in a continuous basal-plus-bolus-infusion setting). The implanted gel displayed anti-inflammatory and anti-foreign-body-reaction properties and promoted the local formation of new blood vessels. The gel is subcutaneously injected before the tip of catheter is inserted into it, and should be generally applicable to CSII catheters and other implantable devices.

Recent advances in oral insulin delivery technologies

With the rise in diabetes mellitus cases worldwide, oral delivery of insulin is preferred over subcutaneous insulin administration due to its good patient compliance and non-invasiveness, simplicity, and versatility. However, oral insulin delivery is hampered by various gastrointestinal barriers that result in low drug bioavailability and insufficient therapeutic efficiency. Numerous strategies have been developed to overcome these barriers and increase the bioavailability of oral insulin. Yet, no commercial oral insulin product is available to address all clinical hurdles because of various substantial obstacles related to the structural organization and physiological function of the gastrointestinal tract. Herein, we discussed the significant physiological barriers (including chemical, enzymatic, and physical barriers) that hinder the transportation and absorption of orally delivered insulin. Then, we showcased recent significant and innovative advances in oral insulin delivery technologies. Finally, we concluded the review with remarks on future perspectives on oral insulin delivery technologies and potential challenges for forthcoming clinical translation of oral insulin delivery technologies.

Biomimetic polymers with phosphorylcholine groups as biomaterials for medical devices

Biomimetic molecular designs can yield superior biomaterials. Polymers with a phosphorylcholine group, a polar group of phospholipid molecules, are particularly interesting. A methacrylate monomer, 2-methacryloyloxyethyl phosphorylcholine (MPC), was developed using efficient synthetic reactions and purification techniques. This process has been applied in industrial production to supply MPC globally. Polymers with various structures can be readily synthesized using MPC and their properties have been studied. The MPC polymer surface has a highly hydrated structure in biological conditions, leading to the prevention of adsorption of proteins and lipid molecules, adhesion of cells, and inhibition of bacterial adhesion and biofilm formation. Additionally, it provides an extremely lubricious surface. MPC polymers are used in various applications and can be stably immobilized on material surfaces such as metals and ceramics and polymers such as elastomers. They are also stable under sterilization and in vivo conditions. This makes them ideal for application in the surface treatment of various medical devices, including artificial organs, implanted in humans.

In Vivo Study of the Inflammatory Tissue Response Surrounding a Novel Extended-Wear Kink-Resistant Insulin Infusion Set Prototype Compared With a Commercial Control Over Two Weeks of Wear Time

BACKGROUND

Infusion set function remains the limiting factor of insulin pump therapy due to nonmetabolic complications. Here, we tested an investigational extended-wear infusion set prototype with a soft, angled, wire-reinforced cannula with three additional side holes, and compared failure mechanisms and tissue response with a commercial Teflon control.

METHODS

A total of 48 Teflon and 48 prototype infusion sets were inserted subcutaneously every other day for 14 days in 12 swine and infused with dilute insulin. After two weeks, tissue around cannulas was excised, and occlusions, leaks, and kinks were determined. Tissue was processed and stained to assess the total area of inflammation (TAI) and the inflammatory layer thickness (ILT) around the cannulas. Data were analyzed using Fisher's exact, analysis of variance-general linear model, Kruskal-Wallis, and post hoc tests.

RESULTS

On average, the TAI surrounding the investigational cannula was 52.6% smaller than around the commercial control. The ILT was 66.3% smaller around investigational cannulas. Kinks occurred in 2.1% (investigational) vs 32.4% (commercial) cannulas (P < .001). There was no difference in occlusion alarms and leaks onto skin.

CONCLUSIONS

The data suggest that the infusion set prototype elicits less inflammation over an extended wear time and is resistant to kinking, compared with a commercial Teflon device. This is consistent with previously published data on the impact of cannula material/angle on the inflammatory tissue response. We highlight the following important aspects of infusion set design: (1) secure skin adhesion, (2) reliable cannula insertion, (3) automatic removal of the stylet, (4) cannula material/design that resists kinking, and (5) minimization of local tissue inflammation.

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.

The Future of Diabetes Therapies: New Insulins and Insulin Delivery Systems, Glucagon-Like Peptide 1 Analogs, and Sodium-Glucose Cotransporter Type 2 Inhibitors, and Beta Cell Replacement Therapy

As the prevalence of diabetes mellitus increases, so too does the number of available treatment modalities. Many diabetic therapies available in human medicine or on the horizon could hold promise in the management of small animal diabetes. However, it is important to consider how species differences in pathophysiology, management practices and goals, and lifestyle may affect the translation of such treatment modalities for veterinary use. This review article aimed to familiarize veterinarians with the more promising novel diabetic therapies and explore their possible applications in the treatment of canine and feline diabetes mellitus.

Insulin Pump-related Inpatient Admissions in a National Sample of Youth With Type 1 Diabetes

BACKGROUND

Insulin pump use in type 1 diabetes management has significantly increased in recent years, but we have few data on its impact on inpatient admissions for acute diabetes complications.

METHODS

We used the 2006, 2009, 2012, and 2019 Kids' Inpatient Database to identify all-cause type 1 diabetes hospital admissions in those with and without documented insulin pump use and insulin pump failure. We described differences in (1) prevalence of acute diabetes complications, (2) severity of illness during hospitalization and disposition after discharge, and (3) length of stay (LOS) and inpatient costs.

RESULTS

We identified 228 474 all-cause admissions. Insulin pump use was documented in 7% of admissions, of which 20% were due to pump failure. The prevalence of diabetic ketoacidosis (DKA) was 47% in pump nonusers, 39% in pump users, and 60% in those with pump failure. Admissions for hyperglycemia without DKA, hypoglycemia, sepsis, and soft tissue infections were rare and similar across all groups. Admissions with pump failure had a higher proportion of admissions classified as major severity of illness (14.7%) but had the lowest LOS (1.60 days, 95% CI 1.55-1.65) and healthcare costs ($13 078, 95% CI $12 549-$13 608).

CONCLUSIONS

Despite the increased prevalence of insulin pump in the United States, a minority of pediatric admissions documented insulin pump use, which may represent undercoding. DKA admission rates were lower among insulin pump users compared to pump nonusers. Improved accuracy in coding practices and other approaches to identify insulin pump users in administrative data are needed, as are interventions to mitigate risk for DKA.

Basal Insulin Degludec and Glycemic Control Compared to Aspart Via Insulin Pump in Type 1 Diabetes (BIGLEAP): A Single-Center, Open-Label, Randomized, Crossover Trial

OBJECTIVE

We compared the efficacy of the second-generation basal insulin degludec (IDeg) to that of insulin aspart via pump using continuous glucose monitoring in patients with well-controlled type 1 diabetes.

METHODS

In this 40-week, single-center, randomized, crossover-controlled trial, adults with well-controlled type 1 diabetes (hemoglobin A1C of <7.5% [<58 mmol/mol]) (N = 52) who were using an insulin pump and continuous glucose monitoring were randomized to 1 of 2 treatments for a 20-week period: a single daily injection of IDeg with bolus aspart via pump or a continuous subcutaneous insulin infusion (CSII) with aspart, followed by crossover to the other treatment. The primary endpoint was time in range (70-180 mg/dL) during the final 2 weeks of each treatment period.

RESULTS

Fifty-two patients were randomized and completed both treatment periods. The time in range for IDeg and CSII was 71.5% and 70.9%, respectively (P = .553). The time in level 1 hypoglycemia for the 24-hour period with IDeg and CSII was 2.19% and 1.75%, respectively (P = .065). The time in level 2 hypoglycemia for the 24-hour period with IDeg and CSII was 0.355% and 0.271%, respectively (P = .212), and the nocturnal period was 0.330% and 0.381%, respectively (P = .639). The mean standard deviation of blood glucose levels for the 24-hour period for IDeg and CSII was 52.4 mg/dL and 51.0 mg/dL, respectively (P = .294). The final hemoglobin A1C level for each treatment was 7.04% (53 mmol/mol) with IDeg, and 6.95% (52 mmol/mol) with CSII (P = .288). Adverse events were similar between treatments.

CONCLUSION

We observed similar glycemic control between IDeg and insulin aspart via CSII for basal insulin coverage in patients with well-controlled type 1 diabetes.

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.