Closing the Loop 24/7 in Adolescents With Type 1 Diabetes

Type 1 diabetes (T1D) is one of the most common chronic childhood diseases requiring lifelong insulin therapy. Children and adolescents with T1D need regular insulin injections or the continuous insulin delivery using an insulin pump in order to keep blood glucose levels normal. We know that keeping blood sugars in the normal range will help prevent long-term diabetes-related complications involving the eyes, kidneys and heart. However, achieving treatment goals can be very difficult particularly due to the risk of low glucose levels (hypoglycaemia). One solution is to use a system where the amount of insulin injected closely matches the blood sugar levels on a continuous basis. This can be achieved by what is known as a \"closed-loop system\" where a small glucose sensor placed under the skin communicates with a computer containing an algorithm that drives a subcutaneous insulin pump. We have been testing such a system in Cambridge over the last five years in children and have found that this system is effective, and superior to usual insulin pump therapy, at maintaining tight glucose control. More recently the system has been tested overnight, in the home setting, for three weeks in adolescents during a pilot single-centre study. The next step is to evaluate use of the closed loop system day and night over a period of 7 days (phase 1) and 21 days (phase 2) in adolescents with type 1 diabetes. In the present study we are planning to study 24 (12 phase 1 ans 12 phase 2) young people aged 10-18 years on insulin pump therapy. This study will involve two 7 (phase 1) and 21 (phase 2) day home study periods, during which glucose levels will be controlled either by an automated closed-loop system or by subjects usual insulin pump therapy combined with continuous glucose monitoring alone in random order. Prior to the closed-loop study period, there will be a training period in the clinical research facility, which will allow participants to familiarise themselves with the closed-loop system before going home. We aim to to determine the effect of the closed-loop computer algorithm in keeping glucose levels between 3.9 and 10.0 mmol/L during the daytime and overnight.