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Patte C.,Roche Holding AG | Pleus S.,Institute For Diabetes Technology Forschungs Und Entwicklungsgesellschaft Mbh | Galley P.,Roche Holding AG | Weinert S.,Roche Holding AG | And 2 more authors.
Journal of Diabetes Science and Technology | Year: 2012

Introduction: Safe and effective closed-loop control (artificial pancreas) is the ultimate goal of insulin delivery. In this study, we examined the performance of a closed-loop control algorithm used for the overnight time period to safely achieve a narrow target range of blood glucose (BG) concentrations prior to breakfast. The primary goal was to compare the quality of algorithm control during repeated overnight experiments. Materials and Methods: Twenty-three subjects with type 1 diabetes performed 2 overnight experiments on each of three visits at the study site, resulting in 138 overnight experiments. On the first evening, the subject's insulin therapy was applied; on the second, the insulin was delivered by an algorithm based on subcutaneous continuous glucose measurements (including meal control) until midnight. Overnight closed-loop control was applied between midnight and 6 a.m. based on hourly venous BG measurements during the first and second nights. Results: The number of BG values within the target range (90-150 mg/dl) increased from 52.9% (219 out of 414 measurements) during the first nights to 72.2% (299 out of 414 measurements) during the second nights (p < .001, χ2-test). The occurrence of hypoglycemia interventions was reduced from 14 oral glucose interventions, the latest occurring at 2:36 a.m. during the first nights, to 1 intervention occurring at 1:02 a.m. during the second nights (p < .001, χ2-test). Conclusions: Overnight controller performance improved when optimized initial control was given; this was suggested by the better metabolic control during the second night. Adequate controller run-in time seems to be important for achieving good overnight control. In addition, the findings demonstrate that hourly BG data are sufficient for the closed-loop control algorithm tested to achieve appropriate glycemic control. © Diabetes Technology Society. Source


Freckmann G.,Institute For Diabetes Technology Forschungs Und Entwicklungsgesellschaft Mbh | Link M.,Institute For Diabetes Technology Forschungs Und Entwicklungsgesellschaft Mbh | Schmid C.,Institute For Diabetes Technology Forschungs Und Entwicklungsgesellschaft Mbh | Pleus S.,Institute For Diabetes Technology Forschungs Und Entwicklungsgesellschaft Mbh | And 2 more authors.
Diabetes Technology and Therapeutics | Year: 2015

Background: Adherence to established standards (e.g., International Organization for Standardization [ISO] 15197) is important to ensure comparable and sufficient accuracy of systems for self-monitoring of blood glucose (SMBG). Accuracy evaluation was performed for different SMBG systems available in Europe with three reagent lots each. Materials and Methods: Test procedures followed the recently published revision ISO 15197:2013. Comparison measurements were performed with a glucose oxidase (YSI 2300 STAT Plus™ glucose analyzer; YSI Inc., Yellow Springs, OH) and a hexokinase (cobas Integra® 400 Plus analyzer; Roche Instrument Center, Rotkreuz, Switzerland) method. Compliance with ISO 15197:2013 accuracy criteria was determined by calculating the percentage of results within ±15% or within ±0.83 mmol/L of the comparison measurement results for glucose concentrations at and above or below 5.55 mmol/L, respectively, and by calculating the percentage of results within consensus error grid Zones A and B. Results: Seven systems showed with all three tested lots that 95-100% of the results were within the accuracy limits of ISO 15197:2013 and that 100% of results were within consensus error grid Zones A and B, irrespective of the comparison method used. Regarding results of individual lots, slight differences between the glucose oxidase method and the hexokinase method were found. Accuracy criteria of ISO 15197:2003 (±20% for concentrations ≥4.2 mmol/L and±0.83 mmol/L for concentrations <4.2 mmol/L) were fulfilled by eight systems with all three lots and by one system with two lots. Conclusions: In this study, seven systems complied with the accuracy criteria of ISO 15197:2013. The results also indicate that the comparison measurement method/system is important, as it may have a considerable impact on accuracy data obtained for a system. Copyright 2015, Mary Ann Liebert, Inc. Source


Freckmann G.,Institute For Diabetes Technology Forschungs Und Entwicklungsgesellschaft Mbh | Schmid C.,Institute For Diabetes Technology Forschungs Und Entwicklungsgesellschaft Mbh | Baumstark A.,Institute For Diabetes Technology Forschungs Und Entwicklungsgesellschaft Mbh | Pleus S.,Institute For Diabetes Technology Forschungs Und Entwicklungsgesellschaft Mbh | And 2 more authors.
Journal of Diabetes Science and Technology | Year: 2012

Background: The accuracy of systems for self-monitoring of blood glucose is important, as reliable measurement results are a prerequisite for therapeutic decisions. Methods: This system accuracy evaluation study was performed according to DIN EN ISO 15197:2003 for 43 Conformité Européenne (CE)-labeled blood glucose (BG) monitoring systems. Measurement results of each system were compared with results of the designated comparison method (manufacturer's measurement procedure): glucose oxidase method (YSI 2300 glucose analyzer) or hexokinase method (Hitachi 917/ cobas 501). Results: Complete assessment according to the International Organization for Standardization (ISO) standard was performed for 34 out of 43 systems, and 27 (79.4%) meet the requirements of the standard, i.e., ≥95% of their results showed at least the minimum acceptable accuracy. For 9 of the 43 systems, complete accuracy assessment was not performed due to an oxygen sensitivity (manufacturer's labeling). The bias (according to Bland and Altman) of all 43 evaluated systems ranged from -14.1% to +12.4%. Conclusions: From the 34 systems completely assessed, 7 systems did not fulfill the minimal accuracy requirements of the ISO standard. The CE mark apparently does not guarantee that all BG systems provide accuracy according to the standard. Because inaccurate systems bear the risk of false therapeutic decisions, regular and standardized evaluation of BG meters and test strips should be requested in order to ensure adherence to quality standards. © Diabetes Technology Society. Source

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