Accuracy of Bolus and Basal Rate Delivery of Different Insulin Pump Systems

Microfluidic-based systems for the management of diabetes

Diabetes currently affects approximately 500 million people worldwide and is one of the most common causes of mortality in the United States. To diagnose and monitor diabetes, finger-prick blood glucose testing has long been used as the clinical gold standard. For diabetes treatment, insulin is typically delivered subcutaneously through cannula-based syringes, pens, or pumps in almost all type 1 diabetic (T1D) patients and some type 2 diabetic (T2D) patients. These painful, invasive approaches can cause non-adherence to glucose testing and insulin therapy. To address these problems, researchers have developed miniaturized blood glucose testing devices as well as microfluidic platforms for non-invasive glucose testing through other body fluids. In addition, glycated hemoglobin (HbA1c), insulin levels, and cellular biomechanics-related metrics have also been considered for microfluidic-based diabetes diagnosis. For the treatment of diabetes, insulin has been delivered transdermally through microdevices, mostly through microneedle array-based, minimally invasive injections. Researchers have also developed microfluidic platforms for oral, intraperitoneal, and inhalation-based delivery of insulin. For T2D patients, metformin, glucagon-like peptide 1 (GLP-1), and GLP-1 receptor agonists have also been delivered using microfluidic technologies. Thus far, clinical studies have been widely performed on microfluidic-based diabetes monitoring, especially glucose sensing, yet technologies for the delivery of insulin and other drugs to diabetic patients with microfluidics are still mostly in the preclinical stage. This article provides a concise review of the role of microfluidic devices in the diagnosis and monitoring of diabetes, as well as the delivery of pharmaceuticals to treat diabetes using microfluidic technologies in the recent literature.

Performance of a Continuous Subcutaneous Insulin Infusion (CSII) Pump With Acoustic Volume and Flow Sensing in Simulated High-Consequence Situations

Goal: An insulin pump's failure to deliver insulin in the right amount at the right time is a preventable cause of hospitalization. We evaluated key performance metrics of a novel insulin pump that prevents "silent insulin non-delivery" caused by blockage, delivery of air and site leakage. This is accomplished via an acoustic sensor that measures the volume of insulin delivered with each pulse in real-time. Methods: We tested long and short-term flow accuracy, occlusion-detection time and pressure, and air management of the new device (ND) versus 3 U.S. commercial insulin pumps (CIPs) using standardized methods. Results: The ND outperformed CIPs on long-term basal flow rate error. Occlusion detection was 5 to 22.5 times faster depending on the basal rate and resulted in significantly lower (2 to 5x) pressures at time of occlusion. With air included in the drug reservoir, the tested CIPs can infuse air without detection, while the ND prevented air delivery without interruption. Conclusions: Bench tests of the ND versus 3 commercially available pumps showed improved occlusion detection and air management without flow performance tradeoffs. Additionally, the lower delivery pressure measured at time of occlusion suggests a substantially lower potential for site leakage at both basal and bolus rates. These enhancements combine to decrease the likelihood of silent insulin non-delivery.

Novel Methods to Understand the Temporal Nature and Accuracy of Delivery for Insulin Infusion Pumps

BACKGROUND

A wide suite of methods are available to evaluate delivery accuracy of insulin pumps. However, these methods do not capture any temporal information, which may be critical for design of artificial pancreas (AP) systems. We propose a novel video microscopy method to understand the delivery accuracy and temporal nature for a new durable pump under development (IFP), and a commercially available pump (Medtronic 722G, M722G).

METHODS

The cannula tip of an infusion set is inserted into a graduated pipette placed under a digital microscope. A video of the delivery is captured to track the fluid meniscus, to measure volumetric delivery rate and accuracy. This was done for a programmed value of 0.5 and 1 U. A similar procedure was adopted to track linear motion of the piston rod, which actuates the reservoir plunger, for a programmed value of 10 U.

RESULTS

It was observed that the commercially available pump delivers insulin in pulses of 0.05 U every two seconds. The mean absolute volumetric delivery error (MAE) for both pumps was found to be within the values reported previously. More importantly, it was found that a significant fraction of the programmed value is delivered, after completion of the planned bolus duration (IFP: 14.31% vs M722G: 9.38% for 1 U delivery).

CONCLUSIONS

The methods presented in this article help understand the delivery dynamics of liquid drug delivery devices. Our results indicate that a significant fraction of insulin delivery happens after the planned bolus duration, which might be important consideration for design of AP systems.

Bench-Side Dose Accuracy of an Open-Source Ultra-Low-Cost Insulin-Pump, With Testing Conducted to IEC 60601-2-24

With the prevalence of diabetes higher than ever, governments and people with diabetes are facing significant treatment and indirect costs associated with managing their condition. An ultra-low-cost insulin pump is a possible solution to improving health disparities. This article presents test results for an insulin-pump built from low-cost components (bill of materials < $US100). All testing was completed in accordance with IEC60601-2-24, and results were benchmarked against a commercial pump. Results showed the ultra-low-cost pump has comparable accuracy to the commercially available insulin pump with testing displaying an overall accuracy of 0.089% and -0.392%, respectively. These results show that an ultra-low-cost pump can accurately deliver insulin in limited bench testing. Testing in other environments and scenarios is required to fully meet IEC60601-2-24 standards.

Comparing Equil patch versus traditional catheter insulin pump in type 2 diabetes using continuous glucose monitoring metrics and profiles

AIMS

It is not clear whether there are differences in glycemic control between the Equil patch and the MMT-712 insulin pump. Our objective was to compare two types of insulin pumps in the treatment of type 2 diabetes mellitus (T2DM), using continuous glucose monitoring (CGM) metrics and profiles.

METHODS

This was a randomized case-crossover clinical trial. Participants were hospitalized and randomly allocated to two groups and underwent two types of insulin pump treatments (group A: Equil patch-Medtronic MMT-712 insulin pump; group B: Medtronic MMT-712-Equil patch insulin pump) separated by a 1-day washout period. Glycemic control was achieved after 7-8 days of insulin pump therapy. Each patient received CGM for 5 consecutive days (from day 1 to day 5). On day 3 of CGM performance, the Equil patch insulin pump treatment was switched to Medtronic MMT-712 insulin pump treatment at the same basal and bolus insulin doses or vice versa. CGM metrics and profiles including glycemic variability (GV), time in range (TIR, 3.9-10.0 mmol/L), time below range (TBR, <3.9 mmol/L), time above range (TAR, >10.0 mmol/L), and postprandial glucose excursions, as well as incidence of hypoglycemia.

RESULTS

Forty-six T2DM patients completed the study. There was no significant difference in parameters of daily GV and postprandial glucose excursions between the Equil patch insulin pump treatment and the Medtronic insulin pump treatment. Similarly, there was no between-treatment difference in TIR, TBR, and TAR, as well as the incidence of hypoglycemia.

CONCLUSION

The Equil patch insulin pump was similar to the traditional MMT-712 insulin pump in terms of glycemic control. Equil patch insulin pump is a reliable tool for glycemic management of diabetes mellitus.

Calibration of insulin pumps based on discrete doses at given cycle times

One application in the medical treatment at very small flow rates is the usage of an Insulin pump that delivers doses of insulin at constant cycle times for a specific basal rate as quasi-continuous insulin delivery, which is an important cornerstone in diabetes management. The calibration of these basal rates are performed by either gravimetric or optical methods, which have been developed within the European Metrology Program for Innovation and Research (EMPIR) Joint Research Project (JRP) 18HLT08 Metrology for drug delivery II (MeDDII). These measurement techniques are described in this paper, and an improved approach of the analytical procedure given in the standard IEC 60601-2-24:2012 for determining the discrete doses and the corresponding basal rates is discussed in detail. These improvements allow detailed follow up of dose cycle time and delivered doses as a function of time to identify some artefacts of the measurement method or malfunctioning of the insulin pump. Moreover, the calibration results of different basal rates and bolus deliveries for the gravimetric and the optical methods are also presented. Some analysis issues that should be addressed to prevent misinterpreting of the calibration results are discussed. One of the main issues is the average over a period of time which is an integer multiple of the cycle time to determine the basal rate with the analytical methods described in this paper.

Design of an open source ultra low cost insulin pump

In this report we present a design for an open source low cost insulin pump. The pump has been designed to provide an alternative to commercially available pumps costing upwards of US$6500, making them inaccessible to many. The hardware described in this article can be produced for a materials cost of US$89.85. Compared to other devices on the market, the design presented has the obvious advantage of being low cost, but is also highly customisable as it is run using open source software. The device is housed in a case of size 85 mm x 55 mm x 25 mm making it small enough to fit in a pocket, and equivalent to other devices on the market. The device is designed to work with insulin cartridges currently available on the market. Power is provided through the use of AAA batteries, and the pump is able to be recharged through a USB mini port. The accuracy of the pump has been tested and compared to data obtained from an in-warranty commercial insulin pump model using an identical testing methodology, with the ultra-low-cost pump performing similarly to the commercial model. The system can be readily extended to be controlled from external bluetooth or wired mobile devices using their built in security, offloading computation from the device and onto a phone.

The Relationship Between Different Bench Test Methodologies and Accuracy of Insulin Infusion Pumps: A Systematic Literature Review

Diabetes technology has rapidly evolved, and insulin infusion pumps (IIPs) have gained worldwide acceptance in diabetes care. The safety of medical equipment is highly discussed, imposing complex challenges in its use. The accuracy of IIPs can be determined through laboratory tests, generally following the IEC 60601-2-24 protocol. Studies have evaluated the accuracy and precision of IIPs, and there are discrepant results. So, we conducted a Systematic Literature Review to assess the methodologies used to evaluate the accuracy of IIPs, organizing the findings in a compiled perspective. The methodology was based on Kitchenham and Biolchini guidelines, and when possible it was carried out the Bayesian meta-analyses to compare the accuracy of IIPs. Most studies used the microgravimetric technique to evaluate the device accuracy, and some proposed adaptations for the standard protocol. The variation of results was recurrent, and the establishment of a protocol, especially to evaluate patch pumps, is necessary. The present study gives enough data to understand the scenario of the IIPs evaluation, as well as the different protocols that can be explored for its evaluation. This highlights the need for a reliable, practical, and low-cost methodology to assist the evaluation of IIPs.

Description of a Novel Patch Pump for Insulin Delivery and Comparative Accuracy Evaluation

A new insulin patch pump for continuous subcutaneous insulin infusion was developed. The pump is composed of reusable and disposable parts and operates with a stepping motor. This pump was compared to a patch pump and a durable pump regarding basal rate and bolus accuracy. Using a microgravimetric method, boluses of 0.2 U, 1 U and 7 U, and a basal rate of 1 U/h were tested. For all pumps, bolus accuracy was higher when larger volumes were delivered. While median deviations were similar for all pumps, there were differences in the precision of individual boluses and when regarding basal rate delivery divided into 1-h windows.

Patch Pumps: What are the advantages for people with diabetes?

AIM

Patch pumps, i.e. insulin pumps without tubing, are an attractive alternative to conventional insulin pumps for people with type 1 diabetes and type 2 diabetes on insulin therapy. In this review, potential patient-relevant advantages and disadvantages of patch pumps are summarized and respective studies on patient-reported outcomes (PROs) are assessed.

METHODS

Relevant studies were identified through a systematic PubMed search. Reference lists in respective articles and Google Scholar were also checked for additional references. Articles in English published before June 30, 2021, were included; no other criteria on publication dates were set.

RESULTS

A total of 12 studies were included. The results of this analysis provide evidence that patch pumps improve quality of life, reduce diabetes-related distress, increase patient satisfaction, and are preferred by patients compared to conventional insulin pumps and multiple daily injection therapy (MDI). However, several methodological limitations of the studies identified constrain the significance of this analysis.

CONCLUSIONS

Despite the limited number of studies evaluating the benefits of patch pumps on PROs, there is increasing evidence that people with diabetes prefer patch pumps. Although there are numerous PROs for patch pumps, it is surprising that this aspect has been relatively understudied. More systematic evaluation studies of the benefits of patch pumps on PROs are needed.

Patch Pumps: Periodic Insulin Delivery Patterns

Recent in vitro experiments with patch pumps (PP) Omnipod (OP), Omnipod DASH (OP-D), A6 TouchCare (A6), and Accu-Chek Solo (ACS) have observed periodic fluctuations in the delivered amount of insulin during basal rate and consecutive bolus delivery in some PP, calling for a more systematic characterization of these periodic delivery patterns. Here, it was found that during basal rate delivery of 1 U/h, some devices of OP, OP-D, and A6 showed deviations of up to ±30% from target delivery that consistently repeated every 5 hours, whereas ACS showed no clear periodicity with considerably lower deviations. Similar results were found during consecutive bolus delivery of 1 U, where deviations repeated consistently every five boluses in some devices of OP, OP-D, and A6. However, there was a large variability in the periodic delivery patterns between individual devices of the same PP model. Examining their pumping techniques indicated a connection between the insulin delivery mechanism and observed delivery patterns of the PP. However, the clinical impact of such patterns is unclear.

Coloured Petri Nets-Based Modeling and Validation of Insulin Infusion Pump Systems

Safety and effectiveness are crucial quality attributes for insulin infusion pump systems. Therefore, regulatory agencies require the quality evaluation and approval of such systems before the market to decrease the risk of harm, motivating the usage of a formal Model-Based Approach (MBA) to improve quality. Nevertheless, using a formal MBA increases costs and development time because it requires expert knowledge and thorough analyses of behaviors. We aim to assist the quality evaluation of such systems in a cost-effective and time-efficient manner, providing re-usable project artifacts by applying our proposed approach (named MBA with CPN—MBA/CPN). We defined a Coloured Petri nets MBA and a case study on a commercial insulin infusion pump system to verify and validate a reference model (as a component of MBA/CPN), describing quality assessment scenarios. We also conducted an empirical evaluation to verify the productivity and reusability of modelers when using the reference model. Such a model is relevant to reason about behaviors and quality evaluation of such concurrent and complex systems. During the empirical evaluation, using the reference model, 66.7% of the 12 interviewed modelers stated no effort, while 8.3% stated low effort, 16.7% medium effort, and 8.3% considerable effort. Based on the modelers’ knowledge, we implemented a web-based application to assist them in re-using our proposed approach, enabling simulation-based training. Although a reduced number of modelers experimented with our approach, such an evaluation provided insights to improve the MBA/CPN. Given the empirical evaluation and the case study results, MBA/CPN showed to be relevant to assess the quality of insulin infusion pump systems.

Modelling and simulation of occlusions in insulin pumps. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2021;2021:1499-1503. [PMID: 34891569 DOI: 10.1109/embc46164.2021.9630219] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

An open source simulation model of the mechanical properties of a fully functional insulin pump was made in Matlab Simscape. The model simulates realistic behavior of an insulin pump, parts of which are validated against real-world systems. Simulations include mechanical forces and internal pressures, and the following fluid dynamics. Failure modes, such as occlusions, can be simulated and the resulting simulations can give new insights on how these failures affect the pump and how to detect them.Clinical relevance- Realistic pump simulations can be used to analyze how pump failures affect the system and in turn how to most effectively detect them before posing a hazard to the user, increasing the safety and reliability of the system.

Piezoelectric Silicon Micropump for Drug Delivery Applications

Subcutaneous injection is crucial for the treatment of many diseases. Especially for regular or continuous injections, automated dosing is beneficial. However, existing devices are large, uncomfortable, visible under clothing, or interfere with physical activity. Thus, the development of small, energy efficient and reliable patch pumps or implantable systems is necessary and research on microelectromechanical system (MEMS) based drug delivery devices has gained increasing interest. However, the requirements of medical applications are challenging and especially the dosing precision and reliability of MEMS pumps are not yet sufficiently evaluated. To enable further miniaturization, we propose a precise 5 × 5 mm2 silicon micropump. Detailed experimental evaluation of ten pumps proves a backpressure capability with air of 12.5 ± 0.8 kPa, which indicates the ability to transport bubbles. The maximal water flow rate is 74 ± 6 µL/min and the pumps’ average blocking pressure is 51 kPa. The evaluation of the dosing precision for bolus deliveries with water and insulin shows a high repeatability of dosed package volumes. The pumps show a mean standard deviation of only 0.02 mg for 0.5 mg packages, and therefore, stay below the generally accepted 5% deviation, even for this extremely small amount. The high precision enables the combination with higher concentrated medication and is the foundation for the development of an extremely miniaturized patch pump.

Evaluation of the Accuracy of Current Tubeless Pumps for Continuous Subcutaneous Insulin Infusion

Background: Recently two new tubeless pumps for insulin therapy were introduced. They were tested for accuracy and occlusion detection and compared with the established patch pump Omnipod^® (OP). Methods: Using a modified setup for tubeless pumps based on IEC 60601-2-24, the basal rate and bolus delivery of the Accu-Chek^® Solo micropump system (ACS) and the A6 TouchCare^® System (A6) were measured with a microgravimetric method. Bolus sizes of 0.2, 1, and 10 U, and basal rates of 0.1 and 1 U/h were evaluated in nine repetitions. For each parameter, mean deviation and number of individual boluses or 1-h basal rate windows within ±15% from target were calculated. In addition, occlusion detection time at basal rates of 0.1 and 1 U/h was determined. Results: Mean deviation of boluses of different volumes in the pumps ranged from -3.3% to +4.0% and 40%-100% of individual boluses were within ±15% of the target. During basal rate delivery, 48% to 98% of 1-h windows were within ±15% of the target with a mean deviation between -5.3% and +6.5%. In general, considerable differences between pump models were observed and deviations decreased with increasing doses. In most parameters, ACS was more accurate, and A6 less accurate, than OP. Mean occlusion detection time ranged from ∼3 to 7.5 h at 1 U/h and was >24 h or absent at 0.1 U/h. Conclusions: In this evaluation, significant differences between the tested tubeless pump models were observed that became most evident when regarding delivery errors over short time and small volumes.

Accuracy of a Low-Cost Continuous Subcutaneous Insulin Infusion Pump Prototype: In Vitro Study Using Combined Methodologies

Considering that infusion devices are safety-critical systems, the main goal of this paper is to evaluate the infusion accuracy and precision of a low-cost insulin infusion pump prototype, using two different methodologies. The first one used a microgravimetric method adapted from IEC60601-2-24, and the second estimated the displacement of the syringe plunger in response to programmed infusions. The low-cost prototype resulted in a compact and functional device with good accuracy. The prototype infused the programmed fluid doses with an average error of 2.2%. The percentage of infusions within ± 5% accuracy was 42.50 and of 84.17% for the ± 15% limit. The developed miniaturized mechanical system presented functionality, precision, and accuracy when coupled to the electronic system, responded well to repeatability tests. Additionally, the results from in vitro tests demonstrated that the performance of the device is satisfactory and comparable to commercial continuous insulin infusion pumps. This study presents a low-cost prototype as a candidate to be used by type 1 diabetic patients in Brazil and developing countries, especially in the context of public health.

Accuracy assessment of bolus and basal rate delivery of different insulin pump systems used in insulin pump therapy of children and adolescents

BACKGROUND

Continuous subcutaneous insulin infusion (CSII) is commonly used in patients with diabetes. Accurate and reliable delivery by insulin pumps is essential for a safe and effective therapy, particularly when using small doses. In this study, accuracy of bolus and basal rate delivery of various available insulin pumps was evaluated.

METHODS

In total, 13 insulin pump systems were tested: eight durable pumps with different infusion sets and one patch pump. Based on IEC 60601-2-24, insulin delivery was measured by recording weight gain of a beaker into which insulin was infused by the pumps. Bolus accuracy was determined by individually weighing 25 consecutive 0.1 or 1.0 U boluses and basal rate accuracy was determined during basal rate delivery of 0.1 or 1.0 U/h for 72 hours. For analyses, basal rate delivery was divided into 1-hour windows and deviation from target was calculated.

RESULTS

Regarding different systems, average 0.1 U bolus delivery was -2% to +9% of the intended volume with 53% to 96% of boluses within ±15% of target. During 0.1 U/h basal rate delivery, most pumps showed an initial over-delivery for the first few hours. Three systems reached a total basal rate error <5%; others showed up to +24%. In general, delivery was more accurate when using larger doses.

CONCLUSIONS

Considerable differences in insulin delivery accuracy were observed between the tested pumps. In general, when using very low doses, accuracy of insulin delivery is limited in most insulin pumps. This should be considered for CSII therapy in children.

All Insulin Pumps Are Not Equivalent: A Bench Test Assessment for Several Basal Rates

Background and Aims: Continuous subcutaneous insulin infusion (CSII) is a widely adopted treatment for type 1 diabetes and is a component of an artificial pancreas. CSII accuracy is essential for glycemic control, however, this metric has not been given sufficient study, especially at the range of the lowest basal rates (BRs), which are commonly used in a pediatric population and in closed-loop systems (CLSs). Our study presents accuracy results of four off-the-shelf CSII systems using a new accurate method for CSII system evaluation. Materials and Methods: The accuracy of four off-the-shelf CSII systems was assessed: Medtronic MiniMed 640G^®, Ypsomed YpsoPump^®, Insulet Omnipod^®, and Tandem t:slim X2^®. The assessment was performed using a double-measurement approach through a direct mass flow meter and a time-stamped microgravimetric test bench combined with a Kalman mathematical filter. CSII accuracy was evaluated using mean of dose error. Mean absolute relative difference (MARD) of error was calculated at different observation windows over the whole series of tests. Peakwise insulin deliverance was assessed regarding stroke regularity in terms of frequency and volume. Results: Mean error values indicate a general tendency to underdeliver with up to -16%. MARD of error shows very wide results for each pump and each BR from 7.4% (2 UI/h) to 61.3% (0.1 UI/h). Peakwise analysis shows several choices for BR adaptation (frequency for Omnipod, volume for Tandem, both for YpsoPump and MiniMed 640G). Precision in interstroke time appears to be better (standard deviation [SD] at 0.1 UI/h: 4.6%-12.9%) than stroke volume precision (SD at 0.1 UI/h 38.3%-46.4%). Conclusions: The accuracy of four off-the-shelf CSII systems is model and BR dependent. CSII imprecision could be due to a variability in volume and/or frequency of strokes for every pump. Some models appear better adapted for the smallest insulin needs, or for inclusion in a CLS. The clinical implications of these delivery errors on glucose instability must be evaluated.

A self-powered insulin patch pump with a superabsorbent polymer as a biodegradable battery substitute

Highly popular insulin patch pumps have in-built non-removable batteries. These batteries are routinely disposed of together with the used pumps as medical waste and end up in landfills. This is an environmental contamination conundrum by design. To address this issue, we proposed a self-powered patch pump that uses a biodegradable superabsorbent polymer (SAP) instead of a battery as a power source to drive the infusion. Continuous infusion rates from 6.1 μL min^-1 to 49.1 μL min^-1 were achieved. Together with valve throttling, basal and bolus infusion rates of ∼10 μL h^-1 (1 U h^-1) and 100 μL (10 U) in ∼11 min could also be implemented for glycemic control. The generated pressure at ∼0.7 psi is also adequate for infusion as it exceeded an adult's maximum peripheral venous pressure of 0.6 psi. Given the current number of patch pump users, the proposed design could prevent ∼100 000 used batteries from entering the medical waste stream and landfill daily. Most importantly, this work highlights the possibility of addressing environmental contamination without compromising on healthcare standards by using SAP as an alternative means of energy storage.

Kalman Filter-Based Novel Methodology to Assess Insulin Pump Accuracy

Background: Insulin pump or continuous subcutaneous insulin infusion (CSII) system is a widely adopted contemporary treatment for type 1 diabetes and is a major component of an artificial pancreas (AP). CSII accuracy is essential for glycemic control and to-date such metric has not been given sufficient study, especially at the range of the lowest basal rate. The gold-standard assessment method IEC (International Electrotechnical Commission) 60601-2-24 has some limitations. Our study presents a new accurate and reactive method for CSII system evaluation based on direct flow measurement. Materials and Methods: A leading-edge assessment method based on a double measurement approach utilizing a direct mass flow meter and a time-stamped microgravimetric bench test was combined with a Bayesian-based mathematical filter (Kalman). The performance of this new method was evaluated while assessing the delivery precision of an off-the-shelf insulin pump at several basal rates. The proposed methodology offers a double reading-volume and flow rate-which provides direct instantaneous flow rate. CSII dose errors were evaluated using mean absolute relative dispersion (MARD) at different time intervals windows over the whole test. Results: The metrological aspect of the measurements and filtering performance were consistent. CSII precision is shown to be different in terms of the flow rate value: MARD_15min (2 UI/h) = 12.7%, MARD_15min (0.5 UI/h) = 20.4%, and MARD_15min (0.1 UI/h) = 65.0%. MARD_240min (2 UI/h) = 8.1%, (0.5 UI/h), MARD_240min (0.5 UI/h) = 18.8%, and MARD_240min (0.1 UI/h) = 18.4%. Instantaneous flow rate results highlight an irregular stroke-based delivery. Conclusion: This new method to assess insulin pump administration has been validated and highlights the current imprecision in insulin delivery, especially for the lowest basal rate, which is mainly used in pediatric cases and AP system delivery. This leading-edge method should be used to precisely compare several CSII performances in those contexts.

Comparative Dose Accuracy of Durable and Patch Insulin Pumps Under Laboratory Conditions

Background: Recent studies demonstrate variable results of the accuracy with which patch pumps infuse insulin. Aim of this evaluation was to measure dose accuracies of the patch pump mylife™ OmniPod^® (OP) in comparison with the durable insulin pump MiniMed^® 640G (MM) simulating real-life clinical situations under laboratory conditions. Methods: Thirty-two OP and 15 MM were tested using insulin aspart at five different boluses (0.5, 1, 5, 10, and 15 international units [IU]) and three basal rates (0.2, 0.6, and 1.8 IU/h) at different time points during a 70 h investigation period. Owing to malfunctions only 22 OP and 11 MM could be analyzed. Dose accuracy was measured by an experimental setting based on IEC 60601-2-24:2012 with determination of weight differences of insulin collection tubes before and after experiments using a precision scale. A maximal tolerance of ±5% for boluses and basal rates was considered adequate according to IEC 60601-2-24:2012. Results: For the five boluses, the percentages of measurement results within the ±5% accuracy threshold were as follows: OP (18.6%, 26.5%, 89.0%, 96.0%, and 96.0%); MM (21.7%, 44.1%, 88.1%, 98.3%, and 100.0%). Both pumps were more accurate at higher bolus volumes (5, 10, and 15 IU), later bolus periods, and if the accuracy threshold was lowered to <10%, <15%, or >15%. For the three basal rates, the percentages within the ±5% accuracy threshold were as follows: OP (66.7%, 22.7%, and 16.7%); MM (14.3%, 0.0%, and 0.0%). Conclusion: This study demonstrates low accuracy for basal rates and single bolus deliveries at low insulin doses for both pump models. Clinicians should be aware of this variability when initiating insulin pump therapy especially in insulin-sensitive patients with low insulin dose requirements.