Clinical requirements for closed-loop control systems.
ABSTRACT Closed-loop (CL) therapy systems should be safe, efficacious, and easily manageable for type 1 diabetes mellitus patient use. For the first two clinical requirements, noninferiority and superiority criteria must be determined based on current conventional and intensive therapy outcomes. Current frequencies of hypoglycemia and diabetic ketoacidosis are reviewed and safety expectations for CL therapy systems are proposed. Glycosylated hemoglobin levels lower than current American Diabetes Association recommendations for different age groups are proposed as superiority criteria. Measures of glycemic variability are described and the recording of blood glucose levels as percentages within, above, and below a target range are suggested as reasonable alternatives to sophisticated statistical analyses. It is also suggested that Diabetes Quality of Life and Fear of Hypoglycemia surveys should be used to track psychobehavioral outcomes. Manageability requirements for safe and effective clinical management of CL systems are worth being underscored. The weakest part of the infusion system remains the catheter, which is exposed to variable and under-delivery incidents. Detection methods are needed to warn both the system and the patient about altered insulin delivery, including internal pressure and flow alarms. Glucose monitor sensor accuracy is another requirement; it includes the definition of conditions that lead to capillary glucose measurement, eventually followed by sensor recalibration or replacement. The crucial clinical requirement will be a thorough definition of the situations when the patient needs to move from CL to manual management of insulin delivery, or inversely can switch back to CL after a requested interruption. Instructions about these actions will constitute a major part of the education process of the patients before using CL systems and contribute to the manageability of these systems.
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ABSTRACT: Pursuit of a closed-loop artificial pancreas that automatically controls the blood glucose of individuals with type 1 diabetes has intensified during the past six years. Here we discuss the recent progress and challenges in the major steps towards a closed-loop system. Continuous insulin infusion pumps have been widely available for over two decades, but "smart pump" technology has made the devices easier to use and more powerful. Continuous glucose monitoring (CGM) technology has improved and the devices are more widely available. A number of approaches are currently under study for fully closed-loop systems; most manipulate only insulin, while others manipulate insulin and glucagon. Algorithms include on-off (for prevention of overnight hypoglycemia), proportional-integral-derivative (PID), model predictive control (MPC) and fuzzy logic based learning control. Meals cause a major "disturbance" to blood glucose, and we discuss techniques that our group has developed to predict when a meal is likely to be consumed and its effect. We further examine both physiology and device-related challenges, including insulin infusion set failure and sensor signal attenuation. Finally, we discuss the next steps required to make a closed-loop artificial pancreas a commercial reality.Annual Reviews in Control 12/2012; 36(2):255-266. DOI:10.1016/j.arcontrol.2012.09.007 · 1.88 Impact Factor
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ABSTRACT: The “Dead-in-bed” syndrome refers to a few subjects with type 1 diabetes (T1D), very young and without forerunners sign except for a high frequency of severe hypoglycemia. These unexplained deaths are up to 10 times more frequent than in the paired non-diabetic population, the sequence could be due to hyperinsulinemia, hypoglycemia, hypokalemia, parallel activation of the sympathetic system and genetic predisposition to trigger severe and fatal rhythm and/or conduction disturbances. However severe nocturnal hypoglycemia is common and rarely causes such dramatic consequences. Hypoglycaemia causes QT prolongation systematically but whose magnitude varies among individuals, probably because of genetic predisposition as in long QT syndrome family. Autonomic neuropathy seems harmless and may even be protective by reducing sympathetic response. Prevention could go through a screening of subjects at risk among youth with T1D. Glucose sensors and closed loop pumps are the first to offer solutions to many of them..Médecine des Maladies Métaboliques 03/2013; 7(2):178–184. DOI:10.1016/S1957-2557(13)70522-4
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ABSTRACT: Many studies have tested clinical and behavioral approaches for improving glycemic control in people with diabetes. We reviewed studies to identify how blood glucose (BG) values have been used in patient-focused clinical research and interventions. We sought to describe the frequency that BG values have been the focus of patient education research and to characterize the different methods to integrate BG into an intervention, the approaches implemented to support patient education, and behavior change, and the nature of communication about BG values. Thirty-four eligible studies were identified that included patient education using BG values. Information regarding the study and intervention characteristics include: (1) characteristics of the study sample, (2) how BG values were obtained, (3) use of a graphical interface for BG values, (4) use of a BG log, (5) BG interpretation and regimen adjustments, (6) recommended actions to patient, (7) modality of intervention, and (8) intervention communication schedule. The review demonstrated that new BG technologies provide outstanding opportunities for greater access to BG data, and for patient support and intervention. However, it also indicated a need to improve and expand support for people with diabetes in their daily use of BG values to maintain and improve glycemic control. In order to make the most sustainable impact on behavior, generalizable skills such as problem solving need to be integrated into BG education.Current Diabetes Reports 09/2013; DOI:10.1007/s11892-013-0428-2 · 3.38 Impact Factor