The Artificial Pancreas in Children and Adolescents with Type 1 Diabetes: Bringing Closed-Loop Home
Type 1 diabetes is one of the most common chronic conditions in childhood and adolescence. Despite ongoing development of more physiological insulin preparations, recent advancements in insulin pump technology and more accurate blood glucose monitoring, in clinical practice it remains challenging to achieve normoglycaemia whilst reducing the risk of hypoglycaemia, particularly in young people with type 1 diabetes.
Closed-loop insulin delivery (the artificial pancreas) is an emerging technology gradually progressing from bench to clinical practice. Closed-loop systems combine glucose sensing with computer-based algorithm informed insulin delivery to provide real-time glucose-responsive insulin administration.
The key objective of my thesis is to evaluate the safety, efficacy and utility of closed-loop insulin delivery in children and adolescents with type 1 diabetes outside of the research facility setting. Results of five clinical trials are presented in the main chapters of this thesis.
In a mechanistic study, the impact of glucose sensor operation duration on efficacy of overnight closed-loop was investigated comparing closed-loop performance on day 1 of sensor insertion to day 3 to 4 of sensor. Twelve adolescents with type 1 diabetes attended the research facility for two overnight visits. The sequence of the interventions was random. Despite differences in sensor accuracy, overnight CL glucose control informed by sensor glucose on day 1 or day 3-4 after sensor insertion was comparable. The model predictive controller appears to mitigate against sensor inaccuracies.
In home settings, overnight closed-loop application was evaluated over three months in 25 children and adolescents with type 1 diabetes aged six to 18 years. The study was conducted at three centres in the UK and adopted a randomised cross-over design. Compared to sensor-augmented pump therapy, overnight home use of closed-loop increased the proportion of time sensor glucose was in target, and reduced mean glucose and hypoglycaemia.
Two randomised crossover studies evaluated the safety and efficacy of day-and-night hybrid closed-loop insulin delivery in young people with type 1 diabetes aged 10 to 18 years over seven days, and 21 days, respectively. A total of 24 subjects were enrolled in this single centre trial. Free-living home use of day-and-night closed-loop in suboptimally controlled adolescents with type 1 diabetes was safe, and improved glucose control without increasing the risk of hypoglycaemia.
Finally, closed-loop technology was assessed in five very young children (aged one to seven years) with type 1 diabetes in a two-period, crossover study. Closed-loop was used during both 3-week intervention periods, either with standard strength insulin (U100), or with diluted insulin (U20). The order of intervention was random. Free-living home use of day-and-night hybrid closed-loop in very young children with type 1 diabetes was feasible and safe. Glucose control was comparable during both intervention periods. Thus, use of diluted insulin during closed-loop insulin delivery might not be of additional benefit in this population.
In conclusion, studies conducted as part of my thesis demonstrate that use of hybrid closed-loop insulin delivery systems in children and adolescents aged one to 18 years in free daily living without remote monitoring or supervision is feasible, safe and effective. My work supports the progression of this technology from research to mainstream clinical practice.