MD-logic artificial pancreas system: a pilot study in adults with type 1 diabetes

Abstract

Objective: Current state-of-the-art artificial pancreas systems are either based on traditional linear control theory or rely on mathematical models of glucose-insulin dynamics. Blood glucose control using these methods is limited due to the complexity of the biological system. The aim of this study was to describe the principles and clinical performance of the novel MD-Logic Artificial Pancreas (MDLAP) System.

Research design and methods: The MDLAP applies fuzzy logic theory to imitate lines of reasoning of diabetes caregivers. It uses a combination of control-to-range and control-to-target strategies to automatically regulate individual glucose levels. Feasibility clinical studies were conducted in seven adults with type 1 diabetes (aged 19-30 years, mean diabetes duration 10 +/- 4 years, mean A1C 6.6 +/- 0.7%). All underwent 14 full, closed-loop control sessions of 8 h (fasting and meal challenge conditions) and 24 h.

Results: The mean peak postprandial (overall sessions) glucose level was 224 +/- 22 mg/dl. Postprandial glucose levels returned to <180 mg/dl within 2.6 +/- 0.6 h and remained stable in the normal range for at least 1 h. During 24-h closed-loop control, 73% of the sensor values ranged between 70 and 180 mg/dl, 27% were >180 mg/dl, and none were <70 mg/dl. There were no events of symptomatic hypoglycemia during any of the trials.

Conclusions: The MDLAP system is a promising tool for individualized glucose control in patients with type 1 diabetes. It is designed to minimize high glucose peaks while preventing hypoglycemia. Further studies are planned in the broad population under daily-life conditions.

Trial registration: ClinicalTrials.gov NCT00541515.

Figure 1

Example of 24-h closed-loop session results conducted with subject 1. A: Glucose trace and the insulin treatment during the 24-h closed-loop trial with subject 1. The top graph shows the CGS readings (black line), reference YSI measurements (♦), and the meal times (▴). The bottom graph shows the insulin treatment delivered by the MDLAP (horizontal line = basal rate, vertical lines with ● = insulin boluses). B: Control variability grid analysis over a time period of 24 h for subject 1. C: Control variability grid analysis overnight (0000–0800 h) for subject 1. The nine zones of the CVGA are associated with different qualities of glycemic regulation: A, accurate control; lower B, benign deviations into hypoglycemia; B, benign control deviations; upper B, benign deviations into hyperglycemia; lower C, overcorrection of hypoglycemia; upper C, overcorrection of hyperglycemia; lower D, failure to deal with hypoglycemia; upper D, failure to deal with hyperglycemia; and E, erroneous control. In both figures, the circles represent the minimum/maximum glucose level taken from the relevant time period glucose readings during home care and the rectangles indicate the levels during the MDLAP-regulated closed-loop session. BG, blood glucose.