ALL INSULIN PUMPS ARE NOT EQUIVALENT: AN INNOVATIVE BENCH TEST ASSESSMENT FOR SEVERAL BASAL RATES
- Sylvain Girardot, France
- Sylvain Girardot, France
- Pauline Jacquemier, France
- Carine Rendekeu, France
- Sébastien Hardy, France
- Jean-Pierre Riveline, France
Abstract
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 (SDomnipod=0.023UI, SDypsopump=0.015UI, SD640G=0.0092UI) except for Tandem (SDtandem=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.