Background and Aims

The purpose of this study was to compare tissue response and insulin bolus spread using straight and angled insulin infusion sets (IIS).

Methods

IIS with different cannula insertion angles (30° or 90°) were inserted subcutaneously every other day for 2 weeks in 11 swine and connected to an insulin pump (basal/bolus pattern). After 2 weeks, an insulin/contrast agent bolus was delivered while recording a pressure profile, evaluating maximum tubing pressure (p_max) and area under the pressure curve (AUC). The tissue-cannula specimen was excised and imaged using micro‑CT to measure bolus surface area (SA) and volume (V). Histopathological analysis of area of inflammation (AI) and thickness of inflammatory layer (LT) surrounding the cannula was carried out. Data were analyzed using ANOVA GLM, Kruskal Wallis, and post-hoc Bonferroni correction.

Results

Insulin infusion through a straight cannula caused significantly higher p_max (p=0.005) and AUC (p=0.014). Bolus SA (30°: 314.0±84.2 mm² vs 90°: 228.7±99.7 mm², p<0.001) and V (30°: 198.7±66.9 mm³ vs 90°: 145.0±65.9 mm³, p=0.001) were larger using an angled IIS. Bolus SA and V decreased significantly over infusion set wear time independent of insertion angle (p<0.05). Straight cannulas caused a greater mean AI (30°: 9.1±4.0 mm² vs 90°: 14.3±8.6 mm², p<0.001) and LT (30°: 0.7±0.4 vs 90°: 1.2±0.7 mm, p<0.001). As the LT increased, p_max increased and bolus volume decreased.

Conclusions

Although a straight IIS is clinically preferred due to easier insertion, our data suggest that angled cannulas elicit less inflammation, and deliver an insulin bolus with lower tubing pressure and greater SA and V.

Background and Aims

In the previous studies, we reported that using a new fluid path design, H-Cap extended wear infusion set (HEWS or EWIS Gen1), extended the infusion set wear time for continuous subcutaneous insulin delivery (CSII) for patients with insulin requiring diabetes. In this study, a newly designed Extended Wear Infusion Set (EWIS Gen2) was evaluated for safety and efficacy for up to 7 days of CSII.

Methods

Twenty-six subjects were recruited with a target of 20 subjects (4 EWIS Gen2 each, until 7-day wear) completing the 1-center, prospective, open label one arm study .

Results

Twenty-one subjects participated in the study with 20 completed, resulting in 82 insertions and 78 wears. After 7 days, the failure rate, including insertion failures, was 19.5% for the EWIS, compared to 50.7% for the Quick-set™ (control) and 30.6% for the HEWS in the previous study, and 64% for Quick-set™ as reported in Patel[1] et al study. When a EWIS was successfully used for 7 days, there was no increase in hyperglycemia or daily insulin requirements.

[1] Patel PJ, Benasi K, Ferrari G, et al. Randomized trial of infusion set function: steel versus teflon. Diabetes Technol Ther. 2014; 16:15-19.

Conclusions

Clinical data obtained from this one arm study confirmed the new fluid path function for extending infusion set wear time. The new EWIS design provided greater than 80.5% survival when worn for 7 days (85% excluding insertion failure), which was a statistically significant improvement when compared to survival curves of a 3-day set worn for 7-days.

Background and Aims

There is emerging evidence of a relationship between diabetes complications and TIR which rivals that with HbA1c.^1-3 Nevertheless, establishing a precise model that predicts HbA1c using TIR has been challenging and complex.^4,5 The distribution of the relationship between HbA1c range and TIR was examined in participants from three MiniMed™ insulin delivery system trials.

Methods

Datasets of 211 children (7-13 years, 10.7[1.8] years) and 573 adolescents and adults (≥14 years, 41.5[17.1] years) from the three-months long MiniMed™ 670G,^6,7 MiniMed™ 640G,⁸ and MiniMed™ 530G⁹ system trials were analyzed. The distributions of TIR (70-180 mg/dL) were evaluated per participant HbA1c range (<6%, 6-7%, 7.1-8%, 8.1-9%, 9.1-10%, and >10%) and R² coefficients were calculated per TIR quintiles.

Results

A spectrum of associations between HbA1c and TIR was observed across the different trials (Figure). When data were stratified into quintiles to characterize TIR subgroups, the R² coefficients ranged from 0.4544 (N=43) to 0.8671 (N=43) for those 7-13 years of age, and from 0.7443 (N=112) to 0.9089 (N=115) for those ≥14 years of age. Best goodness of fit was observed for participants ≥14 years.

Conclusions

The TIR quintiles from MiniMed™ insulin delivery system clinical trials demonstrated a wide variation in the degrees of glucose control within the same HbA1c range for pediatric and adult participants with type 1 diabetes. The TIR provides the quality of HbA1c that an individual patient has achieved and a basis from which to further improve glycemic control. Further studies are required to determine if TIR or HbA1c may better predict diabetes complications.

Background and Aims

As the access to diabetes technology has improved, the spectrum of treatment modalities for T1DM has diversified. We aim to examine different treatment modalities in a large, international diverse cohort of children and adolescents from the SWEET-Registry.

Methods

Subjects with ≥ 1year T1DM duration, aged ≤18 years and documented pump/sensor usage during the period August 2017-July 2019 were selected and stratified in four categories: Injections; Injections+Sensor; Pump; Pump+Sensor. HbA1c and proportion of patients with DKA or severe hypoglycemia (SH) were analyzed. Linear/logistic regression models adjusted for demographics, region and Gross-Domestic-Product (GDP)-per capita were applied.

Results

25,654 Subjects, (median age 13.80 [Q1;Q3: 10.60; 16.40, 95%CI] years; males 51.41 %; diabetes duration 5.18[2.99;8.25] years) were included in the analysis.

^§Adjusted for demographics, region, and GDP; * p-value <0.05; **p-value <0.01

Conclusions

Lower HbA1c and DKA were observed in subjects using technology (pump +/- sensor). Pump use was associated with lower rate of SH, while sensor use was associated with more SH. Residual confounding,preferential use of sensors in patients at risk or increased awareness of SH may explain these findings.

Background and Aims

Continuous subcutaneous insulin infusion (CSII) is a widely-adopted treatment for type 1 diabetes and a component of the artificial pancreas (AP). CSII accuracy is essential for glycaemic control and such metric has not been given sufficient study, especially at the range of the lowest basal-rates. Our study presents accuracy results of four off-the-shelves CSII systems using a new accurate method for CSII system evaluation.

Methods

CSII systems accuracy was assessed by a double measurement approach utilizing a direct mass flow meter and a time-stamped micro-gravimetric test bench combined with a Kalman mathematical filter. CSII accuracy were evaluated using mean of dose error. Mean absolute relative dispersion (MARD) of error was calculated at different observation windows over the whole test. Peak-wise insulin deliverance was assessed regarding stroke regularity in terms of frequency and volume.

Results

MARD of error shows very wide results for each pump and each basal-rate from 7.3%(2U/h) to 61.3%(0.1U/h). Peak-wise analysis shows several strategies for basal-rate adaptation (frequency for Omnipod, volume for Tandem, both for Ysopump and Minimed640G). 0.1UI/h tests highlight insulin stroke overall bad volume reproducibility (SD_omnipod=0.023UI, SD_ypsopump=0.015UI, SD_640G=0.0092UI) except for Tandem (SD_tandem=0.0039UI).

Conclusions

Accuracies of the four off-the-shelves CSII systems are both model and basal-rate dependent. CSII imprecision could be due to a variability of volume and/or frequency of strokes for every pump. Some models appear more adapted for the smallest insulin needs, or for inclusion in a closed-loop system. The implication of these delivery errors on glucose instability must be evaluated.