Additional Signals for Exercise, Stress and Sleep and Prediction of Glucose Levels for AP Systems

The focus of the proposed work is to determine the most informative variables for meals, exercise, acute stress and sleep (MESS), identify select sensors that report these variables, and develop the algorithms to detect the occurrence of MESS, to discriminate them and to determine their characteristics. Research is needed to identify which wearable devices report the most informative and predictive variables of MESS with desired precision and accuracy, determine the best location to wear them for collecting reliable and informative data, and to distill accurate knowledge from data reported by wearable sensors. Data and their interpretation should be informative for various types of physical activities, stages of sleep, and types and intensities of acute stress, and concurrent occurrence of MESS factors.

In the first year of the research, the investigators will use several devices to collect data and evaluate their information content and contribution to improvement of serum glucose prediction, best locations for collecting accurate and reliable information, and their acceptance by users. In the second year of the project, we will select a single wearable device, conduct additional clinical and free-living experiments at-home to assess the contributions of the information from the wearable device selected in improving the accuracy of glucose prediction and the performance of the multivariable AP.

The objectives of the proposed research are to determine the most informative variables and sensor locations to capture reliable and accurate information that complement glucose concentration measurements (CGM) and to develop algorithms to determine the presence of exercise, stress or sleep at any given time for estimating glucose concentrations and making control decisions by a multivariable artificial pancreas system. The proposed research will be conducted by achieving the following specific aims:

To systematically perturb the MESS factors within standardized experiments in the laboratory and at home for analyzing their effects and interactions on glucose concentrations; to identify the most informative and reliable measurement approaches (i.e. types of wearable sensors and locations on body) for discriminating MESS factors; to develop quantitative relations that identify the type and features of specific MESS activities, to develop algorithms to detect the presence of specific MESS activities, identify them, and predict glucose concentrations with recursive models in real time (for future integration with adaptive AP control systems); and to evaluate the performance of the multivariable models with data from wearable devices and CGM in closed-loop control with AP during exploratory clinical experiments.

The study will take place over a period of 3-4 weeks for a total of 6 study visits. The subjects will be continuously monitored using CGM (DEXCOM [US G5 PLATINUM]); 3 activity of the following activity monitor(s); (Empatica E4, BiostampRC™, Equivital™ Life Monitor) and Actigraph throughout the night. In addition, the subjects will use a sleep monitor (Zmachine® Insight \& Insight+ Model DT-200 and Zephyr Bioharness) throughout the 3-week period. Subjects will come in for a study visit 3 times during the first week during which the investigators will measure the subjects' oxygen capacity and muscular strength during a peak exercise stress test (peak V02) and a test of maximal muscle strength (1-RM), respectively. The results of this testing will establish a baseline from which we can calculate the intensity of submaximal aerobic and resistance exercise bouts. The next 3 study visits will occur over the following 3-4 weeks. During this time the subjects will perform activities that produce physiological and psychological stress alone, in combination or proximal to each other. Women will have a urine pregnancy test before each day of data collection. In addition, the subjects will perform a number of physical activities at home that will be scheduled with the research assistant. The research assistant will telephone the subjects periodically and have the subjects perform stressful activities, such as mental challenges.