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    2 Information about hybrid closed loop systems

    Clinical need and practice

    Type 1 diabetes

    2.1 It is estimated that approximately 400,000 people in the UK are living with type 1 diabetes, including around 29,000 children. In type 1 diabetes, a person's blood glucose level becomes too high (hyperglycaemia) because there is no, or very little, production of insulin by the pancreas. Blood glucose levels can only be regulated by giving insulin to prevent hyperglycaemia. If type 1 diabetes is not well controlled, people are at risk of long-term complications of hyperglycaemia, including microvascular damage such as retinopathy and blindness, nephropathy and neuropathy. They are also at increased risk of macrovascular complications such as ischaemic heart disease, stroke and peripheral vascular disease.

    2.2 The goal of treating type 1 diabetes is to keep blood glucose within a healthy range by providing the body with supplemental insulin. If the level of circulating insulin becomes too high, blood glucose levels can become too low leading to hypoglycaemia (also known as a hypo).

    2.3 Managing type 1 diabetes usually involves:

    • lifestyle adjustments

    • regularly measuring blood glucose levels

    • multiple daily insulin injections

    • continuous subcutaneous insulin infusion (CSII)

    • periodic assessment of blood glucose control.

    Blood glucose monitoring can be done by self-monitoring (capillary blood testing), or by real-time continuous (rtCGM) or intermittently scanned continuous glucose monitors (isCGM). Long‑term monitoring of blood glucose control can be done by measuring HbA1c level, which is the average plasma glucose over the last 3 months. Time in range is a measure of blood glucose control that shows the percentage of time a person spends within a target glucose range (3.9 to 10 mmol/litre). Time below range (less than 3.9 mmol/litre) is associated with increased risk of severe hypoglycaemia, while time above range (more than 10 mmol/litre) indicates increased risks of complications and diabetic ketoacidosis.

    2.4 NICE's recommendations on blood and plasma glucose in type 1 and type 2 diabetes in children and young people, type 1 diabetes in adults and diabetes in pregnancy recommend that people with type 1 diabetes should aim for a target HbA1c level of 48 mmol/mol (6.5%) or lower to minimise the risk of long-term complications from diabetes.

    The interventions

    2.5 Hybrid closed loop (HCL) systems use a mathematical algorithm to automatically deliver insulin in response to continuously monitored interstitial fluid glucose levels. They use a combination of real-time glucose monitoring from a CGM device and a control algorithm to direct insulin delivery through CSII. Different HCL systems are available and some are built by combining interoperable devices from different companies. Because of the large number of combinations of components available to the NHS, this appraisal considers HCL systems as a class of technologies rather than individual components or systems. Expert advice received by NICE during scoping suggested that in practice, minimal differences in outcomes would be expected between systems if used as intended. The choice of components or system is based on a person's preference. Any systems available in the future need to be able to show interoperability and be equivalent to current systems in terms of patient benefits.

    2.6 At the time of scoping the following systems and interoperable combination systems were available:

    • The smart guard control algorithm (Medtronic) with the guardian CGM sensor (Medtronic) and either the Minimed 670G or 780G insulin pump (Medtronic). These components are not available for use with components from other companies.

    • Control-IQ control algorithm (Tandem Diabetes Care) with Dexcom G6 CGM sensor (Dexcom) and t:slimX2 insulin pump (Tandem Diabetes Care).

    • CamAPS FX control algorithm (Camdiab) with Dexcom G6 CGM sensor (Dexcom) and either the Dana RS or Dana-I insulin pump (Advanced Therapeutics UK Ltd).

    • Omnipod 5 automated insulin delivery system (Insulet) with Dexcom G6 CGM sensor (Dexcom) and Omnipod tubeless insulin pod (Insulet).

    This is not an exhaustive list and other systems and interoperable component systems are available.

    The comparators

    2.7 There are 2 comparators:

    • rtCGM with CSII (non-integrated)

    • isCGM with CSII (non-integrated).


    2.8 A range of HCL systems are available from different companies. Individual components of different systems are sometimes combined. The external assessment group received NHS supply chain costs for the various systems at current prices. The appraisal model base case used an unweighted average of the 4-year cost from various companies. This resulted in a 4-year total cost of £22,975 and an average annual cost of £5,744.

    2.9 To give an incremental cost-effectiveness ratio of £20,000 per quality-adjusted life year gained, the companies will need to agree a discount with NHS England, on behalf of the relevant health bodies, for HCL systems available to the NHS. The size of the discount is commercial in confidence.