Technology overview

This briefing describes the regulated use of the technology for the indication specified, in the setting described, and with any other specific equipment referred to. It is the responsibility of healthcare professionals to check the regulatory status of any intended use of the technology in other indications and settings.

About the technology

CE marking

The MiniMed 640G system is a class IIb medical device. The manufacturer, Medtronic, received a CE mark in January 2015.


The MiniMed 640G system is an integrated sensor‑augmented pump therapy system. It consists of a continuous glucose monitor and an insulin pump. The system uses a disposable glucose sensor (Enlite), which is inserted under the skin of the abdomen by the user using an automatic device supplied with the system, and secured with a small self‑adhesive patch. It continuously measures glucose levels in the interstitial fluid, which lag about 15 minutes behind capillary blood glucose levels measured using a finger prick. The sensor is replaced at least every 6 days. The sensor is attached to a non‑implanted transmitter (Guardian 2 Link), which sends the data wirelessly to the insulin pump or a stand‑alone monitor. The transmitter is approximately the size of a 2 pence piece and lies almost flat against the skin. The insulin pump or monitor displays the glucose data on a screen and can plot trend‑lines. The sensor readings are updated every 5 minutes.

The insulin pump, which weighs about 92 g and is 5.3 cm×9.6 cm×2.5 cm, can be clipped to a belt or be carried in a pocket. An insulin reservoir that can hold up to 300 units of insulin is fitted to the pump. An infusion set carries insulin from the reservoir to the body through a subcutaneous catheter. The reservoir and infusion set are changed every 2 to 3 days. The pump delivers a continuous basal rate of insulin needed for normal body functioning. This is a personalised background level of insulin agreed between the user and clinician and accounts for approximately one‑half of daily insulin requirements. The MiniMed 640G has 48 basal rates, from which the user can set up a personal daily basal pattern with different rates at various times of the day. Up to 8 of these basal patterns may be programmed, for example, to allow for different needs at weekends. More bolus insulin can be delivered by the user on demand through the pump controls to cover an expected rise in blood glucose levels, typically after meals. The system is waterproof, and designed to be worn continuously.

The MiniMed 640G system includes the proprietary SmartGuard algorithm, which uses data from the interstitial continuous glucose sensor to stop insulin delivery if hypoglycaemia, as defined by the user with a personalised pre‑set low glucose limit, is predicted to happen within 30 minutes. The system automatically restarts insulin delivery when it is predicted that blood glucose levels will be above the pre‑set low, within a minimum of 30 minutes and a maximum of 2 hours from suspension. It is possible to set up to 8 suspend limits per day to account for individual lifestyles and meals. The MiniMed 640G is a further development of the MiniMed Paradigm Veo system, which only stops delivering insulin once hypoglycaemia is present, and automatically stays suspended for 2 hours unless manually turned back on.

The MiniMed 640G system provides information to the user by alarms, alerts or messages, depending in the seriousness of the problem. An alarm warns the user that insulin delivery is being prevented, for example, if the insulin flow is blocked or the battery needs replacing; alarms must be addressed straight away. An alert makes the user aware of a situation that may need attention, for example, a low insulin reservoir or a low battery. A message gives information about the status of the pump. In addition, the system gives alerts if sensor glucose levels are predicted to reach pre-set high or low levels in the next 30 minutes, or are rapidly changing. Users are notified of alarms and alerts using sound or vibration. A siren is sounded if an alarm is not cleared within 10 minutes.

Setting and intended use

The MiniMed 640G is intended for use by children and adults with type 1 diabetes who have difficulty managing their blood glucose levels by self‑monitoring and multiple daily insulin injections. It is also designed for people who cannot easily identify hypoglycaemic events, have a history of severe hypoglycaemia, are susceptible to night‑time hypoglycaemia, or who fear daytime or night‑time hypoglycaemia. Continuous glucose monitoring is not designed to completely replace conventional finger‑prick tests but rather to give extra information on the direction (increase or decrease) and speed of blood glucose trends, and can be used to help guide therapy adjustments.

Current NHS options

Type 1 diabetes is currently managed by monitoring blood glucose levels and insulin replacement therapy. This usually involves multiple daily insulin injections, with the doses adjusted according to blood glucose levels, and planned meals and exercise. Healthcare professionals give education and training to support people using insulin.

The NICE guideline on the diagnosis and management of type 1 diabetes in adults recommends that continuous glucose monitoring is not routinely offered and should only be considered when standard management of blood glucose levels has not worked or been difficult. However, the NICE guideline for children and young people with type 1 diabetes recommends that children and young people who have severe hypoglycaemic events, or cannot recognise hypoglycaemic events or communicate about the symptoms of hypoglycaemia, should be offered continuous glucose monitoring.

NICE technology appraisal guidance on continuous subcutaneous insulin infusion for the treatment of diabetes mellitus recommends that insulin pump therapy be considered for adults and children aged 12 years and older if they have not been able to reach target glycated haemoglobin levels with multiple daily injections or have disabling hypoglycaemia. For children younger than 12 years, insulin pump therapy is recommended if multiple injections are impractical or inappropriate.

NICE diagnostics guidance on integrated sensor-augmented pump therapy systems recommends the MiniMed Paradigm Veo in selected patients and in specific circumstances (please refer to the published guidance for detailed information).

NICE is aware of the following CE‑marked devices that appear to fulfil a similar function to the MiniMed 640G:

  • MiniMed Paradigm Veo System (Medtronic)

  • Vibe and G4 PLATINUM continuous glucose monitoring system (Animas and Dexcom).

The MiniMed Paradigm Veo System automatically suspends insulin delivery if glucose levels fall to a pre‑agreed level, however it does not predict when it is safe to restart insulin delivery. The user must manually restart insulin delivery or it automatically restarts after 120 minutes.

NICE is not aware of any other CE‑marked devices that have a similar function to the predictive low glucose suspend and resume algorithm used by the MiniMed 640G system.

Costs and use of the technology

The MiniMed 640G system has the following costs (excluding VAT):

  • MiniMed 640G insulin pump: £2995

  • Guardian 2 Link kit (includes transmitter and charger): £490.

The Guardian 2 Link transmitter is compatible with only the MiniMed 640G insulin pump.

The consumables needed for the system cost (excluding VAT):

  • Enlite glucose sensors (pack of 10): £525

  • MiniMed Mio infusion sets (pack of 10): £109.50

  • MiniMed insulin reservoirs (pack of 10): £29.50.

The MiniMed 640G insulin pump has a 4‑year warranty, and needs 1 new AA (1.5 V) battery. Battery life is typically 7 to 14 days depending on the type of battery and the amount of use. The glucose sensors are replaced every 6 days, so each pack of 10 will last about 2 months. The infusion set and insulin reservoir need to be replaced at least every 3 days, so each pack of 10 will last about 1 month. The monthly cost of consumables is about £400 (excluding VAT).

People who use the MiniMed 640G will still need to have capillary blood glucose tests to calibrate the device to ensure the glucose sensor maintains its accuracy over time, and before changes in insulin therapy. A capillary blood glucose meter costs at least £15, and the test strips that are used with the meter cost about £20 for a pack of 50. Lancets for finger‑prick blood tests cost around £10 per 100.

For people using continuous subcutaneous insulin infusion, several other manufacturers produce continuous glucose monitors that do not link automatically to an insulin pump as well as pump systems with a range of specifications and functionalities. The pumps typically cost £2000–3000 with variable prices for consumables.

Continuous glucose monitors that do not link automatically to an insulin pump cost about £1000 for a transmitter and monitor, with extra cost for sensors.

People who inject insulin manually use an insulin pen that costs about £30 to £40. Needles for reusable insulin pens cost around £20 for a pack of 100. Most people have 4 blood tests and insulin injections per day, so the monthly cost of self‑monitoring and injection is around £84, excluding the cost of insulin.

Likely place in therapy

The MiniMed 640G system would be used in place of other reactive continuous glucose monitoring and insulin pump systems when standard management of blood glucose levels has not worked or been problematic, according to the NICE guideline on type 1 diabetes in adults. NICE has produced diagnostics guidance on 2 other integrated sensor-augmented pump therapy systems for managing blood glucose levels, which recommends the MiniMed Paradigm Veo system as an option for managing blood glucose in people with type 1 diabetes if they have episodes of disabling hypoglycaemia despite optimal management with continuous subcutaneous insulin infusion. As with standard management, people using the system will still need to have regular consultations with their diabetes team, which may include consultants, nurses, dietitians and pharmacists, to ensure that the system is working satisfactorily.

Specialist commentator comments

One specialist commentator noted that although many people are satisfied with conventional insulin therapy or insulin pumps, there is a specific minority group of patients who have hypoglycaemic unawareness or recurrent disabling hypoglycaemia. This group meets the NICE criteria both for an insulin pump and for continuous glucose monitoring. Along with 2 other specialist commentators, they agreed that the MiniMed 640G system may be appropriate for this group of people. In addition, 1 specialist commentator has found the system useful for reassuring families when nocturnal hypoglycaemia is feared, and for those with young children who find it difficult to recognise hypoglycaemia.

Two specialist commentators noted the importance of setting insulin rates and alarms to suit the individual needs of the person, and of regularly reviewing these settings. This is especially relevant for children because insulin needs change with growth and development. One commentator noted that if they are not reviewed regularly, people may ignore or switch off alarms.

One commentator pointed out that the system is complex and not an easy option compared with multiple daily injections. They highlighted the importance of assessing the person's motivation and knowledge of their diabetes management, and giving training.

All of the specialist commentators noted difficulties in adopting and using the MiniMed 640G system. One commentator reported that the Enlite continuous glucose sensor, which is part of the system, was not as accurate as the Dexcom continuous glucose sensor used with the Animas Vibe insulin pump, and the system could suspend insulin delivery when, in the clinician's opinion, it was not necessary; that is, when glucose levels were low but stable. They stated that rebound hyperglycaemia sometimes happened when insulin delivery was suspended for too long, while another specialist commentator noted that there is concern that the suspension of insulin administration could lead to loss of glycaemic control. One specialist commentator reported difficulties in adopting the system due to the cost and NHS restrictions, but in their limited experience, the pump with continuous glucose monitoring will help to prevent admissions for the small number of patients with severe hypoglycaemia or a lack of awareness and may therefore be cost effective.

One specialist commentator noted that the battery life seems very short compared with other pumps, which use lithium batteries that can last 2–3 months.

One specialist commentator noted that the evidence base is very limited. They added that the cohorts included in the studies were already using sensor‑augmented pumps and so were self‑selected as being able to use the technology. The commentator stated that use of such pumps requires the support of an experienced team, and it remains to be seen how they perform outside of the research environment.

Equality considerations

NICE is committed to promoting equality, eliminating unlawful discrimination and fostering good relations between people with particular protected characteristics and others. In producing guidance and advice, NICE aims to comply fully with all legal obligations to:

  • promote race and disability equality and equality of opportunity between men and women

  • eliminate unlawful discrimination on grounds of race, disability, age, sex, gender reassignment, pregnancy and maternity (including women post‑delivery), sexual orientation, and religion or belief (these are protected characteristics under the Equality Act 2010).

The manufacturer does not recommend the use of this product by people whose impaired vision or hearing does not allow full recognition of the pump signals and alarms.

Patient and carer perspective

Representatives from 3 diabetes charities, that is, Diabetes UK, JDRF and INPUT, contributed the following patient and carer perspectives:

  • Hypoglycaemia is a major effect of intensive insulin therapy and can be a barrier to effective treatment of diabetes. The MiniMed 640G is the first step towards a fully automated insulin delivery system, which would be a tremendous benefit to people with type 1 diabetes and their carers.

  • Many people with type 1 diabetes have a continuous fear of hypoglycaemia, and anything that can reduce or remove that fear is beneficial for their quality of life.

  • Parents of children with type 1 diabetes often check their blood glucose during the night because of the fear of night‑time hypoglycaemia. Those who use continuous glucose monitors with alarms find them very reassuring.

  • For those people who have lost hypoglycaemia awareness, this type of technology can be a life saver. If a patient with type 1 diabetes is not conscious of their blood glucose level dropping, then a continuous glucose monitoring system that can provide an alarm for the user to take appropriate action is very beneficial. The added advantage of the MiniMed 640 system is that it can take action to prevent the hypoglycaemia happening, which is clinically beneficial because people who have lost their hypoglycaemia awareness can often regain it if they are able to avoid hypoglycaemia for a time. Preventing hypoglycaemic episodes in this group is therefore about more than just preventing seizures, fits and potential 'dead in bed syndrome', but could also improve quality of life and overall quality of care by helping people recover hypoglycaemia awareness.

  • People with type 1 diabetes are very scared of the associated complications, particularly blindness, kidney failure and amputation. National Diabetes Audit data (Health and Social care Information Centre) show that the group most at risk is young men and women between the ages of 15 and 34 years, who are 4 and 6.5 times respectively more likely to die than their peers. This group also has the worst metabolic control. They really struggle to keep diabetes under control, often deliberately keeping their blood glucose levels much higher than recommended to avoid hypoglycaemia, but in so doing, risk having diabetic ketoacidosis. For these people, a system that can help prevent hypoglycaemia and very high blood glucose levels could have real benefits, including cost‑saving benefits for the NHS in preventing diabetic ketoacidosis and the cost of complications.

  • The benefits of using continuous subcutaneous insulin infusion and continuous glucose monitoring, especially with new technology such as the SmartGuard, are what many people with diabetes want. This is the first step in the move towards an artificial pancreas being available, allowing people with diabetes and their carers to lose some of the diabetes distress, which current systems cannot help with.