Practice Update: Diabetes

CONFERENCE COVERAGE 10

Hybrid Closed-Loop Systems Prove Safe And Effective in Controlling Glucose Levels in Children and Adults with Type 1 Diabetes Results of two trials demonstrated safety and efficacy, and reduction in exercise-induced hypokalemia, using closed- loop systems in children and adults with type 1 diabetes. Results of the two trials were reported at the American Diabetes Association’s 77th Scientific Sessions, from June 9–13. C ontinuous glucose monitoring devices provide around-the-clock information on blood glucose lev- 4% of readings <70 mg/dL when at home and not using the hybrid-closed loop sys- tem. Mean fasting glucose level following overnight use of the closed-loop system was 136 ± 24 mg/dL. closed-loop system that responds to phys- ical activity automatically.

The study included 20 adults with type 1 diabetes who used wearable, wireless sen- sors including heart rate and accelerometer sensors to detect the onset of aerobic exercise automatically and communicate, calculate, and deliver the appropriate insu- lin and/or glucagon dose needed to avoid hypoglycemia. In random order, participants used various systems, including: • A single-hormone closed-loop system that doses insulin only • A dual-hormone closed-loop system that doses both insulin and glucagon • A predictive, low-glucose suspend system that shuts off insulin if glucose is predicted to go too low • Patients’ usual current standard of care whereby they controlled their glucose levels using their own methods Participants attended four, 4-day outpa- tient visits at which they exercised for 45 minutes at 60% VO2max on days 1 and 4 in a human performance lab. They com- pleted at least one at-home exercise session to determine the amount of time in hypoglycemia. Subjects entered estimated carbohy- drate intake into the insulin pump, which automatically delivered a portion of the

els in patients with type 1 diabetes. Insulin pumps allow insulin to be administered subcutaneously throughout the day. Over the recent past, researchers com- bined the technology of continuous glucose monitoring and insulin pumps to form closed-loop systems, which allow for continuous insulin delivery through a pump throughout the day and night based on glucose measurements provided every 5 minutes by the continuous glucose monitor. Hybrid closed-loop indicates that the system is continuously adjusting insulin delivery. At mealtime, however, the patient enters the amount of carbohydrates being consumed, and the insulin pump deter- mines the meal dose of insulin. Hybrid Closed-Loop System in Children Age 6–12 Years With Type 1 Diabetes Using a Personalized Model Predictive Control Algorithm Bruce A. Buckingham, MD, of the Lucile Salter Packard Children’s Hospital, Stanford University in Stanford, California, explained that children with type 1 diabetes are more sensitive to insulin than adolescents and adults, and are at increased risk of severe hypoglycemia overnight. Dr Buckingham and colleagues performed an inpatient research center study to eval- uate the safety and feasibility of a new hybrid closed-loop system. They combined a patch pump with Bluetooth-enabled sensor built into the receiver and a person- alized model predictive control algorithm. The study included 12 children aged 6-12 years with type 1 diabetes whose average age was 9 years and average diabetes duration was 4 years. The trial consisted of a 36-h, inpatient, closed-loop assess- ment with meals ranging from 30-90 g of carbohydrates and limited physical activity to examine glycemic outcomes. Continuous monitoring data indicated that 69.2% of overall glucose values were between the desired range of 70-180 mg/ dL. Overnight, 82% of values were within range. Participants’ average glucose level was 157 mg/dL, and 2% of readings were <70 mg/dL using the system compared to

Dr Buckingham concluded that the auto- mated glucose control algorithm performed well and was safe during day and night use in children with type 1 diabetes. “Hybrid closed-loop systems do a great job improving glucose control overnight, low- ering the risk of hypoglycemia significantly, and allowing patients and their families to get a good night’s sleep,” he said. “These systems also assist patients dur- ing the day in decreasing the magnitude of both high- and low-glucose fluctuations,” he added. “Many patients prefer wearing an ‘untethered’ patch pump, which pro- vides more flexibility to enjoy physical activities without worrying about infusion set detachments.” He continued, “The hybrid system provides additional protection against hypoglyce- mia, resulting in improved quality of life for children with diabetes. Longer outpa- tient studies are needed in subjects using the system under their home living condi- tions. The device is being tested in many age groups and under many different conditions.” Single and Dual-Hormone Closed-Loop Glucose Control with Automated Exercise Detection to Prevent Hypoglycemia in Type 1 Diabetes Peter G. Jacobs, PhD, of Oregon Health & Science University in Portland, explained that patients with type 1 diabetes encounter difficulty in controlling their blood glucose levels while exercising. Aerobic exercise can cause sharp drops in blood sugar, leading to hypoglycemia. Single- and dual-hormone closed-loop systems automate the dosing of insulin, or insulin plus glucagon, to help these patients avoid exercise-induced hypoglycemia by reducing insulin delivery and increasing glucagon in response to exercise. Dr Jacobs and colleagues developed and evaluated single- and dual-hor- mone closed-loop systems. They set out to determine whether exercise-related hypoglycemia can be reduced through a

© ADA/Todd Buchanan 2017

PRACTICEUPDATE DIABETES