A sensor in the arm may help thousands with diabetes avoid having frequent finger prick tests.
The device, called Eversense, is slightly larger than a pill and is implanted under the skin in a five-minute procedure.
It then continuously monitors blood sugar levels from the fluid that bathes cells just below the skin and transmits the data to a smartphone.
If blood sugar levels drop too low or are too high, the patient receives an alert on their phone, so they can take insulin to reduce the levels or eat something sugary to increase them.
The device also has a vibration alert in case the phone is off or there is no signal.
It stops patients needing regular finger prick tests, which can be painful. It has been approved in Europe, but is not yet available in the UK, though it is being considered by the NHS.
A study presented recently at the Diabetes Technology Meeting in Maryland, U.S., showed it was accurate and effective when tested on 90 adults with type 1 or type 2 diabetes for 90 days.
If this type of monitoring was used more widely, it could help to reduce hospital admissions and diabetic complications, according to the charity Diabetes UK.
It is particularly useful for patients with type 1 diabetes —where the immune system mistakenly attacks healthy cells in the pancreas, which then cannot produce insulin. It affects 400,000 Britons — about 10 per cent of all adults with diabetes.
Patients with this type of diabetes currently monitor blood sugar levels by taking between four and ten finger-prick tests a day, which helps them work out how much insulin they need.
But this method only gives a snapshot of blood sugar levels at that time, so it can be difficult to tell if they are rising or falling. It means that despite regular checking, patients may still suffer attacks of hypoglycaemia — when levels drop too low, causing shakiness, sweating and confusion.
Eversense is a continuous glucose monitor. Some patients already use devices such as the FreeStyle Libre and Enlite, which work in a similar way, but these need to be replaced every seven to 14 days. In contrast, Eversense will last for 90 days before it needs replacing.
It comprises a pill-sized implant and a small, square patch stuck to the skin above the device. Patients are given a local anaesthetic in the arm. A 1cm incision is made in the skin to insert the sensor and is then closed.
‘Research shows that continuous glucose monitoring can improve overall diabetes control and reduce complications such as diabetic coma and foot amputations by reducing the amount of time someone spends with very high or very low blood sugar,’ says Simon O’Neill, director of health intelligence at Diabetes UK.
However, these devices cost several thousand pounds a year and the Eversense is likely to be similarly priced.
‘People pay for continuous monitoring devices themselves and even those who fit the criteria to have one on the NHS can find their local health authority does not fund them for everyone,’ says Mr O’Neill.
‘However, in the long term, the cost benefit could be substantial when you factor in the A&E visits and extra medical support needed when someone suffers from uncontrolled hypoglycaemia or very high sugar levels.
‘Complications can include seizures, foot disease and even amputations, which reduce mobility and quality of life.’
He says more evidence is needed about the efficacy and cost effectiveness of these devices.
‘All the systems use different methods of measuring glucose. It may be this one is more durable than other methods.’