Closing the Loop in Adults With Type 1 Diabetes - Alcohol Consumption

People with type 1 diabetes need regular insulin injections or continuous delivery of insulin using an insulin pump. Keeping blood sugars in the normal range is known to reduce the risk of long term complications involving the eyes, kidneys and heart. However, achieving treatment goals can be very difficult as the tighter we try to control blood glucose levels, the greater the risk of the person developing episodes of low glucose levels (hypoglycaemia). One solution is using 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. This system is being developed in Cambridge and is undergoing trials in children and adults with type 1 diabetes. Results thus far show that the system is very effective at preventing hypoglycaemia and maintaining blood glucose levels in target range.

We plan to test the closed loop in various challenging conditions faced by patients in daily life. One of these is the consumption of alcohol, which can give rise to delayed hypoglycaemia in patients with diabetes. The studies will be done in a clinical research facility under supervised conditions. Subjects will attend for two study nights where they will receive a specific volume of alcohol with an evening meal. On one night this will be followed by closed loop algorithm control of their insulin overnight. On the other (control) night subjects will remain on their usual pump therapy regime overnight.

Inclusion criteria

• Type 1 diabetes, as defined by WHO for at least 6 months or confirmed C-peptide negative
• On insulin pump therapy for at least 3 months

Exclusion criteria

• Non-type 1 diabetes mellitus
• Any physical/psychological disease likely to interfere with the study
• Taking medication likely to interfere with interpretation of results
• Known/suspected allergy against insulin
• Clinically significant nephropathy, neuropathy or retinopathy as judged by the investigator
• Unstable blood glucose control, including recurrent severe hypoglycaemia as judged by the investigator
• Current pregnancy/breastfeeding
• Total daily insulin dose > 1.4 IU/kg
• HbA1C > 10% within the last 3 months
• Unable/unwilling to consume the necessary quantity of alcohol stated in the study protocol