In those without diabetes insulin is automatically secreted according to requirement. The background insulin secretion rate will vary depending on need, and is affected by many factors e.g. activity or stress levels. When a person eats the rise of glucose is sensed and insulin automatically secreted to keep the glucose within a narrow range.
People with Type 1 diabetes cannot make insulin to control their blood glucose. Insulin is therefore required as treatment. This is given subcutaneously by injection or using an infusion pump. Both background insulin is required and boluses of insulin given when carbohydrate is eaten.
It is difficult to accurately calculate and deliver the correct amount of insulin. More recently standard treatment involved giving one of two injections of long acting insulin and more frequent injections of fast acting insulin when carbohydrate is ingested. The dose of insulin is determined by measuring the ambient glucose level, knowing the amount of carbohydrate in any meal and predicting activity during the subsequent four or five hours.
Insulin pumps can be used to provide a pre-tuned variable background insulin infusion with manual intervention to deliver boluses of insulin with food.
In Scotland many people have now replaced finger prick glucose testing with flash glucose monitoring. This uses a small subcutaneous needle that senses subcutaneous glucose levels and, when scanned this sensor will provide a measure of subcutaneous glucose and information on the last 8 hours of glucose values (Flash Glucose monitoring). This system does not currently link to an insulin pump.
The Tandem insulin pump has recently become available in NHS Scotland for those already established on pump therapy.
The Dexcom G6 continuous glucose monitoring (CGM) system provides continuous glucose monitoring (without requiring any scanning by the patient) but is not currently funded within NHS Scotland, except for special circumstances. This system does communicate via bluetooth with the T-slim insulin pump.
The Tandem Control IQ insulin delivery system uses the link between the dexcom glucose sensor and pump to control the background insulin delivery and has been shown to work well in those studied. Patients still have to administer insulin when ingesting carbohydrate. This system is described as a hybrid closed loop system.
Problems that can potentially occur using this system include loss of communication between sensor and pump (bluetooth or wired connection), the algorithm not working or glucose readings out with the set ranges resulting in the automatic system turning off.
It is also unknown how acceptable the 'loss of control' is to a more general diabetes population as individuals with diabetes are used to making all the insulin dose decisions very frequently across each day. Confidence in these systems, both by patients and clinicians will be vital if these are to be introduced into more general use.
Therefore, the potential for these systems to have a major impact for people with diabetes is clear, but further understanding of the effectiveness and acceptability of such systems in the Scottish population is required.
The Investigator's aim is to investigate the effect of this system compared to current 'best practice' in Scotland, to gain experience in using this system and to investigate the acceptability of this system in the Scottish population.
