Evaluating the Impact of Human Factors and Pen Needle Design on Insulin Pen Injection

The Needle Shield Size and Applied Force of Subcutaneous Autoinjectors Significantly Influence the Injection Depth

BACKGROUND

This study examines how shield-triggered autoinjectors (AIs), for subcutaneous drug delivery, affect injection depth. It focuses on shield size and applied force, parameters that could potentially lead to inadvertent intramuscular (IM) injections due to tissue compression.

METHOD

A blinded ex-vivo study was performed to assess the impact of shield size and applied force on injection depth. Shields of 15, 20, and 30 mm diameters and forces from 2 to 10 N were investigated. The study involved 55 injections in three Landrace, Yorkshire, and Duroc (LYD) pigs, with injection depths measured with computed tomography (CT). An in-vivo study, involving 20 injections in three LYD pigs, controlled the findings, using fluoroscopy (FS) videos for depth measurement.

RESULTS

The CT study revealed that smaller shield sizes significantly increased injection depth. With a 15 mm diameter shield, 10 N applied force, and 5 mm needle protrusion, the injection depth exceeded the needle length by over 3 mm. Injection depth increased with higher applied forces until a plateau was reached around 8 N. Both applied force and size were significant factors for injection depth (analysis of variance [ANOVA], P < .05) in the CT study. The FS study confirmed the ex-vivo findings in an in-vivo setting.

CONCLUSIONS

The study demonstrates that shield size has a greater impact on injection depth than the applied force. While conducted in porcine tissue, the study provides useful insights into the relative effects of shield size and applied force. Further investigations in humans are needed to confirm the predicted injection depths for AIs.

Optimising Insulin Injection Techniques to Improve Diabetes Outcomes

The effectiveness of therapy in patients with diabetes depends on the correct use of the insulin injection technique. However, despite many established recommendations and evidence that an effective insulin injection technique is essential to improve glycaemic control and minimise the risk associated with diabetes, there is still a need to identify impediments to the insulin injection technique among patients and create awareness among patients and healthcare professionals about the importance of the optimisation of insulin injection techniques. This review focuses on the recent advancements in delivery devices, insulin injection technique teaching methods, monitoring, and complication management and highlights regional best practices and recommendations for optimising injection techniques to improve diabetes outcomes.

Imaging of large volume subcutaneous deposition using MRI: exploratory clinical study results

Subcutaneous (SC) delivery is a preferred route of administration for biotherapeutics but has predominantly been limited to volumes below 3 mL. With higher volume drug formulations emerging, understanding large volume SC (LVSC) depot localization, dispersion, and impact on the SC environment has become more critical. The aim of this exploratory clinical imaging study was to assess the feasibility of magnetic resonance imaging (MRI) to identify and characterize LVSC injections and their effect on SC tissue as a function of delivery site and volume. Healthy adult subjects received incremental injections of normal saline up to 5 mL total volume in the arm and up to 10 mL in the abdomen and thigh. MRI images were acquired after each incremental SC injection. Post-image analysis was performed to correct imaging artifacts, identify depot tissue location, create 3-dimensional (3D) SC depot rendering, and estimate in vivo bolus volumes and SC tissue distention. LVSC saline depots were readily achieved, imaged using MRI, and quantified via subsequent image reconstructions. Imaging artifacts occurred under some conditions, necessitating corrections applied during image analysis. 3D renderings were created for both the depot alone and in relation to the SC tissue boundaries. LVSC depots remained predominantly within the SC tissue and expanded with increasing injection volume. Depot geometry varied across injection sites and localized physiological structure changes were observed to accommodate LVSC injection volumes. MRI is an effective means to clinically visualize LVSC depots and SC architecture allowing assessment of deposition and dispersion of injected formulations.Trial Registration: Not applicable for this exploratory clinical imaging study.

Needle Technology for Insulin Administration: A Century of Innovation

Innovations in syringe and pen needle (PN) technology over the last 100 years have led to important advances in insulin delivery for people with diabetes, paralleling the strides made in developing recombinant DNA human insulin and insulin analogs with varying onset and duration of action. In this review, the history of advances in insulin delivery is described, focusing on progress in syringe, needle, and PN technologies. The early glass and metal syringes that required sterilization by boiling have been replaced by disposable, single-use syringes or pens with clear labeling for precise insulin dosing. The early needles ranging in length from 19 to 26 mm that required manual sharpening against a whetstone have been replaced by syringe needles of 6 mm and PNs of 4 mm in length as slender as 34 gauge. Imaging studies using ultrasound and computed tomography measured the thickness of skin and subcutaneous tissue layers to show feasibility of targeted insulin administration with shorter needles. These developments, coupled with innovations in needle/PN wall and tip structure, have led to improved injection experience for people with diabetes. It is also important to acknowledge the role of injection technique education, together with these advances in injection technology, for improving clinical outcomes and patient satisfaction. With continued projected growth of diabetes prevalence, particularly in developing countries where expensive and complex insulin delivery systems may not be practical, insulin syringes and pens will continue to serve as reliable and cost-effective means of insulin delivery for people with diabetes.

Patients' Experience of New Technologies and Digitalization in Diabetes Care in Germany

BACKGROUND

Little is little known about how people with diabetes experience advancing digitization and new technologies in diabetes.

RESEARCH QUESTION

What are the attitudes of people with diabetes (or, in the case of children with diabetes, their parents) toward digitization and advancing technology in diabetology? What significant advantages and disadvantages do they see, and how do they assess current developments of digitization in diabetology (eg, hybrid closed-loop systems, do-It-Yourself (DIY) closed-loop systems, data protection, and data donation)?

MATERIAL AND METHOD

3,427 people with diabetes (47.7% female, 65.6% type 1 diabetes (T1D), 25.5% type 2 diabetes (T2D), 8.1% parents of children with diabetes; 0.8% other type of diabetes, age 49.2 ± 19.3 years) were interviewed with an online survey.

RESULTS

Overall, survey participants had a very positive attitude toward digitization (82.6%) and considered the potential for optimizing diabetology through digitization to be very high (78.8%). The highest rated advantages of digitization were "greater personal responsibility and self-determination in therapy" (80.0%), "better quality of treatment" (80.0%), and "better communication with the doctor/diabetes team" (77.3%), while the highest rated disadvantages were the "error-proneness of digital applications" (35.9%), the "risk of misuse of patient data" (32.3%) and the "fear that digitization will replace the doctor in many cases" (31.1%). The possibility of evaluating and analyzing glucose data by means of software, and AID systems, and the possibility of improving the interoperability of the various applications are currently rated as the most significant topics.

CONCLUSIONS

The vast majority of people with diabetes are very positive about new technologies in diabetology and expect that it will improve and simplify their diabetes therapy and reduce the burdens associated with diabetes. In particular, people with type 1 diabetes have high expectations for AID systems, viewing them as a kind of "technical cure" for their diabetes.

Enabling faster subcutaneous delivery of larger volume, high viscosity fluids

OBJECTIVES

Many current subcutaneous (SC) biologic therapies may require >1 mL volume or have increased viscosity, necessitating new delivery system approaches. This study evaluated 2-mL large-volume autoinjector (LVAI) delivery performance across varying solution viscosities and design inputs to assess the design space and identify configurations that produce practical injection times.

METHODS

Investigational LVAI delivery duration and volume, depot location, and tissue effects were examined in both air and in vivo models across various pre-filled syringe (PFS) cannula types (27 G Ultra-thin wall [UTW], 27 G special thin wall [STW], or 29 G thin-wall [TW]), drive spring forces (SF_LOW or SF_HIGH), and Newtonian solutions (2.3-50 centipoise [cP]).

RESULTS

Within each design configuration, increasing PFS internal diameters and spring forces reduced delivery times, while increasing viscosity increased times. The 27 G UTW PFS/SF_HIGH combination achieved shorter delivery times across all injection conditions, with 2 mL in vivo durations <15 seconds at ≤31 cP and routinely <20 seconds at 39 and 51 cP, with nominal and transitory tissue effects.

CONCLUSION

PFS cannula and spring force combinations can be tailored to achieve various injection durations across viscosities, while UTW PFS enables faster rates to potentially better accommodate human factors during LVAI injection, especially at high viscosity.

Diabetes Technology Meeting 2021

Diabetes Technology Society hosted its annual Diabetes Technology Meeting on November 4 to November 6, 2021. This meeting brought together speakers to discuss various developments within the field of diabetes technology. Meeting topics included blood glucose monitoring, continuous glucose monitoring, novel sensors, direct-to-consumer telehealth, metrics for glycemia, software for diabetes, regulation of diabetes technology, diabetes data science, artificial pancreas, novel insulins, insulin delivery, skin trauma, metabesity, precision diabetes, diversity in diabetes technology, use of diabetes technology in pregnancy, and green diabetes. A live demonstration on a mobile app to monitor diabetic foot wounds was presented.

Population Pharmacokinetics of Cotadutide in Subjects with Type 2 Diabetes

BACKGROUND AND OBJECTIVES

Cotadutide is a balanced dual glucagon-like peptide-1/glucagon receptor agonist under development for the treatment of nonalcoholic steatohepatitis and chronic kidney disease with type 2 diabetes. The objectives of the analysis were to characterize the population pharmacokinetics of cotadutide following daily subcutaneous injection in subjects with type 2 diabetes and to evaluate the effect of demographic and clinical variables of interest on cotadutide pharmacokinetics.

METHODS

This study analyzed 8834 plasma concentrations of cotadutide from 759 subjects with type 2 diabetes who received daily subcutaneous doses from 20 to 600 μg from six clinical studies. The impact of covariates on cotadutide pharmacokinetics was quantified, and body weight effect on cotadutide exposure was further evaluated using a simulation approach. The model performance was evaluated through prediction-corrected visual predictive checks.

RESULTS

A one-compartment model with first-order absorption and elimination described cotadutide pharmacokinetic data well. The mean values for cotadutide apparent clearance, apparent distribution volume, absorption rate constant, and half-life were 1.04 L/h (interindividual variability [IIV]: 26.5%), 18.7 L (IIV: 28.7%), 0.343 h^-1 (IIV: 38.6%), and 12.9 h, respectively. Higher body weight, lower albumin, and higher alanine aminotransferase were associated with an increase in cotadutide clearance, while an increase in anti-drug antibody titers was associated with a decrease in cotadutide clearance. These statistically significant effects were not considered clinically significant and did not warrant dose adjustment. Effects of other tested baseline covariates (age, sex, body mass index, hemoglobin A1c, renal function, duration of diabetes) were not found to statistically significantly affect cotadutide pharmacokinetics.

CONCLUSIONS

Cotadutide pharmacokinetics was adequately described by a one-compartment linear model with first-order absorption and elimination. Body weight-based dosing is not necessary for cotadutide based on the simulation using the final population pharmacokinetic modeling. This model will be used to evaluate exposure-response relationships for efficacy and safety in different indications that are being studied for cotadutide.

Novel cannula design improves large volume auto-injection rates for high viscosity solutions

A prototype reusable large-volume (2 mL) autoinjector (LVAI) was designed to compare injection performance of a novel 27 gauge ultra-thin wall (UTW) pre-filled syringe (PFS) cannula (8 mm external cannula length, 14.4 mm total needle length) against an existing 27 gauge special thin wall (STW) PFS cannula (12.7 mm external cannula length, 19 mm total needle length) across a range of injectate viscosities (2.3–30 cP) in a series of in vivo feasibility studies in swine. The UTW cannula had an approximately 30% greater cross-sectional lumen area than the STW cannula. The target exposed needle length was adjusted to ensure appropriate needle penetration depth and achieve injectate deposition in the subcutaneous (SC) tissue. Delivery time and volume, injection site leakage, injectate depot location, and local tissue effects were examined. The STW and UTW cannulae both provided effective SC delivery of contrast placebo solutions, and were able to accommodate injectate viscosity up to 30 cP without quantifiable leakage from the tissue and with minor tissue effects which resolved within 1–2 hours. Delivery times at each viscosity were significantly different between PFS types with the UTW PFS producing faster delivery times. In a histological substudy of the UTW cannula using injectate viscosities up to 50 cP, injection site reactions were rare and, when present, were of minimal severity. This series of studies demonstrates the feasibility of LVAI SC injection and informs autoinjector and PFS design considerations. Use of a UTW cannula may enable more rapid LVAI injections with minimal tissue effects, especially for higher viscosity formulations.

Insulin Injection Practices in a Population of Canadians with Diabetes: An Observational Study

INTRODUCTION

Proper insulin injection technique has demonstrated positive clinical outcomes in patients with diabetes. A Canadian-based practice reflective was undertaken to evaluate the current state of understanding of injection technique practices by patients administering insulin, and the importance physicians place on proper injection technique.

METHODS

Twenty-four sites across Canada completed a practice profile survey and enrolled adult non-pregnant patients with either type 1 or type 2 diabetes injecting insulin using an insulin pen. Seven areas of proper injection technique to be evaluated were identified by the study steering committee: size of injection site, use of a skin lift, needle reuse, length of the needle, duration of the needle in the skin, injection into lipohypertrophic tissue, and applied injection force. During a scheduled visit, each patient filled out the Injection Technique Survey and the physician documented the answers via an electronic database.

RESULTS

Almost all physicians surveyed agreed (96%) that proper insulin injection technique is important or very important and 80% indicated they were either completely confident or fairly confident in discussing overall insulin injection technique. All patients surveyed were making at least one insulin injection technique error within the following categories: applied injection force (76%), area size of injection site (64%), duration of pen needle in skin (61%), pen needle reuse (39%), performs a skin lift with a 4 or 5 mm needle (38%), uses a longer pen needle than required (34%), and injection of insulin into lipohypertrophic tissue (37%).

CONCLUSION

Patients commonly make insulin injection errors. Patient and physician education on optimal insulin injection technique continues to be an unmet medical need for the treatment of patients with diabetes. Prospective trials examining the impact of new technology, diabetes educational teams, and e-learning as educational interventions are potential avenues to explore in future studies to support improved insulin injection technique.

User experiences with second-generation 32-gauge × 4 mm vs. thinner comparator pen needles: prospective randomized trial

OBJECTIVE

Two similarly designed studies compared user experiences with a second-generation extra-thin-wall, 5-bevel 32 G × 4 mm pen needle (PN) with redesigned hub versus four thinner commercially available PNs.

METHODS

Adults (18-75 years old) with type 1 or type 2 diabetes and ≥3 months of experience with pen injectors qualified for single-visit, single-blinded randomized studies. The investigational 32 G PN was compared with three 33-34 G × 3.5-4 mm PNs in Study 1 and one 34 G × 4 mm PN in Study 2. Participants completed 12 abdominal injections of 0.3 mL sterile saline using insulin pens in 6 pairs, each comprising one investigational 32 G PN and one comparator PN in random order. After each injection pair, participants compared injection pain via relative 150 mm visual analog scale (VAS) and perceived dose delivery force via relative 5 point Likert scale. Adjusted models tested injection pain scores (primary endpoint) for noninferiority and, if met, then for superiority. ClinicalTrials.gov identifiers: NCT03878758 and NCT03878745.

RESULTS

The investigational 32 G PN met noninferiority as well as superiority criteria for less injection pain vs. each comparator (p < .01), with adjusted mean relative VAS scores 9.1-17.6 in Study 1 (n = 154) and 7.3 in Study 2 (n = 55). The investigational 32 G PN was also superior vs. each comparator PN in requiring less relative perceived force to deliver the dose (p < .01).

CONCLUSIONS

The investigational 32 G PN was associated with less participant-reported injection pain and less perceived dose delivery force compared with four thinner PNs, suggesting no additional pain reduction or force reduction benefit conferred by the thinner PNs.