Continuous glucose monitoring in type 1 diabetes

New testing options on the NHS

So the news that for the first time, a fingerprick-free testing device – the Freestyle Libre monitoring system – is to be made available on the NHS Drugs Tariff from November 2017 has been met with excitement. Until now, people have either had to pay for it privately (at a cost of about £58 for the reader and 2 months of sensors costing about £114) or apply for funding on an ‘exceptional case’ basis, called an Individual Funding Request. But this doesn’t mean an end to fingerprick testing for everyone, and there could be trying times ahead for patients trying to access it.

Glucose monitoring using a 'flash' system involves inserting a tiny sensor under your skin once a fortnight. This measures the glucose in your interstitial fluid (Ithe fluid that surrounds your cells). To get a reading, you wave a reading device over the sensor. The level of sugar in your interstitial fluid lags behind your blood sugar levels by a few minutes, especially if your blood sugar is changing rapidly. That means you may still need a fingerprick test before you take more insulin or glucose for a hypo on the basis of a reading.

Nor is Flash glucose monitoring the only option we can expect to be available on the NHS Drugs Tariff in years (or even months) to come. Several companies have developed Continuous Glucose Monitoring (CGM) systems, which automatically record the glucose levels in your interstitial fluid and send them to a monitor without you swiping over the sensor. In practical terms, perhaps the biggest difference is that this allows an alarm to be set up, alerting you to high or low blood sugar without you actively taking a reading. According to Diabetes UK, ‘Flash GM is not a less expensive alternative for CGM, rather the different technologies have different uses for specific groups in particular circumstances’.

These developments include the first long-term implantable CGM device, the Eversense XL, which is implanted under the skin. The table below gives a summary of the main comparisons between the two technologies.

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Why test more?

Hypoglycaemia causes a variety of symptoms including

• Hunger, irritability, anxiety, tremor and blurred vision in the early stages

• Confusion, irrational behaviour, collapse and even death in later stages.

People who suffer more than one ‘severe’ hypo (needing outside assistance) a year can lose their driving license. And people who lose ‘hypo awareness’ are at much higher risk of severe symptoms. I’ve seen mothers who don’t feel safe looking after their kids, and men terrified to leave the house in case they’re suddenly hit by a hypo.

On average, people with type 1 diabetes test their blood sugar just over 5 times a day. But NICE (the National Institute for Health and Care Excellence) says that testing up to 8 times a day in Type 1 diabetes is cost effective. This is based on evidence that on average, more testing correlates with tighter blood glucose control and lower HbA1c. NICE recommends that people with type 1 diabetes should be aiming for an HbA1c (a measure of your average blood glucose over the last 3 months or so) of 48mmol/mol – a level almost equivalent to someone who doesn’t have diabetes. High blood sugar carries a risk of damage to the kidneys, eyes and nerves, as well as heart attack and stroke.

Who might be eligible?

NICE has laid out criteria for people with type 1 diabetes who should be considered for CGM, although this does not include the Freestyle Libre. They include:

• More than one severe hypoglycaemia brought on by no obvious preventable cause

• Complete loss of hypo unawareness

• Frequent problematic hypos without early warning symptoms

• Extreme fear of hypos causing problems or distress

• Not being able to get your HbA1c under 75mmol/mol (9%) despite blood sugar at least ten times a day

In addition, you need to fulfil all the following criteria to qualify for CGM:

• The intended user is committed to using CGM at least 70% of time and keep it regularly calibrated

• The user is on multiple daily insulin injections or insulin pump therapy

• The Health team providing CGM has expertise in its use

• It should only be continued if as a result, HbA1c drops to and stays below 53 mmol/mol (7%), of ir HbA1c is reduced by 27mmol/mol (2.5%)

Even if you do fulfil all these conditions, getting access to Freestyle Libre is not a given. Firstly, there are negotiations to be had with ‘local health economies’ about funding – that’s management speak for a possible postcode lottery. Secondly, Diabetes UK makes it clear that ‘Flash GM is not the appropriate tool for those who have completely and irreversibly lost their hypoglycaemia awareness, which means they cannot recognise when their glucose levels are dangerously low. In this instance CGM which provides alarms is more appropriate.’ This may give cash-strapped CCGs an excuse to withhold funding, at least until CGM is available on the NHS Drugs Tariff.

Further down the line?

Several CGM devices with an alarm have been developed. As yet, none are available on the NHS Drugs Tariff. However, with the approval of the Freestyle Libre device and the recommendations of NICE on CGM, it is highly likely that more will follow.

Within the next year or two, I anticipate patients at high risk of hypoglycaemia being offered the option of Flash GM or CGM, and weighing up their personal preferences. It’s not here yet, and there may be some battles ahead – but after years of people with type 2 diabetes getting all the headlines, it looks like it’s finally the turn of people with type 1.