The technology

The t:slim X2 insulin pump (Tandem Diabetes Care) is for continuous subcutaneous insulin delivery to manage blood glucose levels in people with type 1 diabetes. The device is up to 38% smaller than other insulin pumps and has a watertight aluminium case and shatter-resistant colour touch screen interface. The flat insulin cartridge accommodates up to 300 units of insulin. Rapid-acting insulin is delivered from the device through thin flexible tubing to a cannula placed under the skin. The infusion site is changed every 2 days to 3 days. The t:slim X2 pump can be altered to give different rates of basal insulin. It also has an integrated bolus calculator that can record carbohydrates, to help with bolus delivery. The device allows 6 profiles to be created for basal insulin delivery depending on the needs of the user.

The t:slim X2 insulin pump can be used as a standalone pump or can integrate with a G6 continuous glucose monitor (CGM; Dexcom). This briefing focuses on the t:slim X2 pump with CGM. The G6 CGM can provide real time glucose measurements by bluetooth from a CGM transmitter. When the pump is used with the G6 CGM additional features, Basal‑IQ or Control‑IQ algorithms are available. Basal‑IQ uses values from the G6 CGM to reduce the frequency and duration of low-glucose events by predicting glucose levels 30 minutes in advance. It can suspend insulin if levels are expected to drop below 4.4 mmol per litre, or if an actual CGM reading is 3.9 mmol per litre or less. Basal‑IQ software is currently being optionally upgraded to Control‑IQ (if existing users want to upgrade and if healthcare professionals think it is clinically appropriate). This is an advanced hybrid closed-loop system. Control-IQ can adjust basal insulin when glucose levels are predicted to go above 8.9 mmol per litre and give a correction bolus if glucose levels are predicted to go above 10.0 mmol per litre. It can also adjust basal insulin if glucose levels are predicted to go below 6.25 mmol per litre and suspend delivery if the predicted value is below 3.9 mmol per litre. Control-IQ also uses activity and sleep settings.

The device has a rechargeable battery, USB ports and the software can be updated remotely using a personal computer during the 4-year warranty of the pump. Patients can also upload their device data using the Diasend (Glooko) or Tidepool (Tidepool Project) diabetes data management systems. Then their doctor or nurse can review patterns in data and help make changes in pump settings when necessary.


The technology combines glucose monitoring using a CGM with advanced algorithms in the insulin pump to predict low glucose and suspend insulin delivery. The Control‑IQ algorithm software can adjust basal insulin levels and give correction doses. The company claims that these systems reduce the effect of hypoglycaemic events and ensure patients are within optimal glucose range more of the time. Using a Dexcom G6 CGM also removes the need for sensor calibration, which uses finger prick testing. The t:slim X2 insulin pump is the only pump currently available in which software can be remotely updated.

Current care pathway

Continuous subcutaneous insulin infusion (insulin pump) therapy is recommended as a treatment option for adults and children 12 years and older with type 1 diabetes if:

  • attempts to meet target haemoglobin A1c (HbA1c) levels with multiple daily injections result in the person experiencing disabling hypoglycaemia or

  • HbA1c levels have remained high (8.5% [69 mmol/mol] or above) with multiple daily injections, despite a high level of care.

Continuous subcutaneous insulin infusion therapy is recommended as a treatment option for children younger than 12 years with type 1 diabetes if multiple daily injections therapy is considered impractical or inappropriate. Children with insulin pumps would be expected to have a trial of multiple daily injections between 12 years old and 18 years old.

Continuous glucose monitoring for adults with type 1 diabetes is recommended for those who have any of the following despite optimised use of insulin therapy and conventional blood glucose monitoring:

  • more than 1 episode a year of severe hypoglycaemia with no obvious preventable cause

  • complete loss of hypoglycaemia awareness

  • more than 2 episodes a week of asymptomatic hypoglycaemia

  • extreme fear of hypoglycaemia

  • hyperglycaemia (HbA1c level of 75 mmol/mol [9%] or higher) that persists despite testing at least 10 times a day.

Children and young people should be offered real-time continuous glucose monitoring with alarms if they have frequent severe hypoglycaemia, impaired awareness of hypoglycaemia, or cannot recognise or communicate symptoms of hypoglycaemia.

The following guidance has been identified as relevant to this care pathway:

Population, setting and intended user

The t:slim X2 insulin pump is for patients with type 1 diabetes when it is appropriate to use insulin pump therapy instead of multiple daily injections. This device would be used in a home setting. The pump is not for use in children under 6 years old. There is no evidence for using the technology in pregnant women, people on dialysis, or people who are critically ill. Users with cognitive, visual and physical impairments may need a care partner to be co‑trained in pump therapy to recognise pump functions, including alerts. The company provides training for healthcare professionals as well as patients when they start using the pump. The company also provides ongoing technical support with a 24‑hour, 7 days a week freephone service.


Technology costs

The company has provided prices for the t:slim X2 insulin pump with associated consumables as well as the cost of the Dexcom G6 CGM. The company states that the insulin pump and consumables will cost a total of £9,501 to £9,701 over a 4‑year period (the duration of the device warranty) or £20,081 to £20,281 with full time use of the CGM (over 4 years, with consumables).

Breakdown of individual devices and consumables:

  • t:slim X2 insulin pump (with 4 year warranty) costs £3,150 with Basal‑IQ or £3,350 if purchased for use with the Control‑IQ algorithm.

  • Insulin cartridges (10‑pack box) cost £32.25.

  • Infusion sets (10‑pack box) cost £89.90.

  • It is estimated that a patient would use around 13 boxes of cartridges and infusion sets each year, totalling £1,588 per year on consumables. This number may be higher if there are any problems with the cartridge or infusion set leading to earlier replacement of consumables.

  • Dexcom G6 CGM: £2,645 per year. This estimate is based on 4 transmitters (£200 each; changed every 3 months) and 36 sensors (£153.75 for a pack of 3; each sensor lasting 10 days).

  • Discounts may be available depending on the volume purchased.

Costs of standard care

Alternative insulin pumps that have compatible CGMs listed are MiniMed 670G (Medtronic), MiniMed 640G (Medtronic), MiniMed 780G (Medtronic) and A6 system (Medtrum). The company states that the MiniMed 670G or 780G with a Guardian Sensor 3 CGM (Medtronic) would be the most comparable system.

The MiniMed 670G insulin pump with CGM starter kit (which includes a Guardian Link 3 transmitter and 5 Guardian Sensor 3s) costs £3,730 (excluding VAT). Guardian Sensor 3 costs £525 for a pack of 10. Each sensor lasts 7 days, leading to a cost of around £2,730 per year.

The MiniMed 640G insulin pump costs £2,995 and the transmitter and charger costs £490 (all excluding VAT). Consumables including glucose sensors, infusion sets and insulin reservoirs cost around £4,800 (excluding VAT) per year. Over 4 years this would cost £22,685.

Resource consequences

The company states that this pump is currently used in over 130 NHS clinics, with over 1,900 patients using the device in the UK. The device could be an alternative to other insulin pumps provided by the NHS. Patients may want to use a compatible CGM for full use of the device functions, such as Basal‑IQ or Control‑IQ. The company also states this device could be used by patients who already have a G6 CGM.