The Freestyle Libre
“My fingers are red raw” Marci says through sighed words. Marci has been testing her blood glucose levels through finger prick testing for 10 years now. She has type 1 diabetes and has to test her blood glucose levels a minimum of four times per day. Marci needs to test her blood glucose levels in order to calculate her insulin doses. This then allows her to keep her glucose levels within target range.
Marci is in fact a fictitious patient. However, she represents so many of my patients who have had the displeasure of having to finger prick test. For some, finger prick testing isn’t such a big deal. For others, particularly needle phobic patients, it’s an anxiety inducing, painful experience. I think we can all agree if there was a way to test your glucose levels without finger prick testing, it would make life much easier and less painful.
One of the reasons I find diabetes so interesting is because it is a disease area with rapid progression. This is in both treatment options and technology. This is why the news Abbots Freestyle Libre is now available on prescription for some NHS patients is exciting.
What is the Freestyle Libre
The Freestyle Libre is a sensor the size of a 50p coin. It measures glucose levels without the need to finger prick test. The sensor has a small needle which is inserted into the back of the arm. This is then held in place by an adhesive on the sensor. The insertion process is painless.
The sensor does not actually measure blood glucose levels. This is because the needle only penetrates into the interstitial fluid which sits between the blood and the skin. This means there is approximately a 7 minute delay between blood glucose levels and the levels the sensor will detect. A video demonstrating how to insert the device can be seen by clicking here.
How it works
Each time you scan your sensor it will automatically record the next 8 hours of glucose data. Therefore, in theory, to capture a full 24 hours dataset you only need to scan 3 times in a day at 8 hour intervals. In reality though patients scan much more frequently than this as the Libre allows you to effortlessly detect your glucose levels as many times as you wish.
You can then upload the data to the Freestyle Libre software system. This will produce key insights into your glucose level behaviour throughout the day. This is particular helpful if seeing a diabetes healthcare professional. They can help you interpret the information to decide what needs to be done in regards to your treatment.
Furthermore, not only does the sensor provide you with your glucose level, it provides the direction of travel for your glucose levels. It does this using arrows next to the reading indicating whether your levels are dropping or rising quickly, gradually or are stable. Particularly with regards to hypoglycaemia this information can be vital. Someone may find their glucose levels are 5mmol/l at the time of scanning but with a downward arrow meaning they can take preventative action.
Who can get one?
In theory, anyone. Abbott allows individuals to self fund the device. Many people were doing this before it was available on prescription and also continue to do so.
For those interested in getting one on prescription the criteria is pretty strict. The criteria also varies from CCG to CCG and so local commissioning bodies ultimately decide the criteria for their own area. However, generally speaking, the criteria is individuals who meet one or more of the following:
- Testing 8 or more times per day
- High HbA1c
- Prone to frequent hypoglycaemia
- Loss of awareness of hypoglycaemia
- Frequent admissions with diabetic ketoacidosis (DKA)
Who should get one?
As you may have guessed from the criteria, the Libre sensor is aimed at those with type 1 diabetes or people following a basal bolus regimen (if you don’t know what a basal bolus is I have previously written on this topic here).
This is because these individuals rely completely on insulin injections in order to control their blood glucose levels. To have stable glucose readings patients need to calculate the correct dose of insulin. Further complicating matters, dietary intake, exercise, stress and illness all impact glucose levels increasing the difficulty calculating correct doses. In other words, their glucose levels can be prone to significant variations.
Therefore, alongside the sensor uploads, the Libre is a great tool to help us understand glucose patterns and adjust medication regimens accordingly. For example, it is possible to see if someone is crashing or spiking upon waking, after eating breakfast, lunch or dinner, from snacks, or exercise.
Who doesn’t need one?
Most people with type 2 diabetes will have no need for one and are unlikely to get one on prescription. To compare, patients with type 1 diabetes need to calculate how much insulin they need to inject based on their current glucose level. This will change at each meal and time of day. They also need to test frequently. Therefore, identifying patterns is useful to tailor treatment options.
A patient only on oral diabetes medications will find little benefit in this data because ultimately we already know the pattern from your HbA1c test (your 3 month average glucose level tested on your annual review). In these patients, the problem is more lifestyle related. Making lifestyle changes will improve the diabetes more so than looking at glucose levels.
The need for a sensor in type 2 diabetes will increase as your treatment escalates. For example, patients treated in a similar manner to type 1 patients may qualify under the above criteria.
How much do they cost?
If not getting one on prescription, a sensor currently costs around £50 and lasts 2 weeks. In other words, about £100 per month. Unfortunately, this currently prices many patients out of obtaining one.
Pro’s of the sensor
The obvious advantage is the reduced need for blood glucose testing. It is painless, quick and efficient.
It is quite discreet in appearance sitting on the back of the arm.
The ability to upload the data is also a huge plus. With more data healthcare professionals are more easily able to advise you. The more data we can access the more accurate we can be with our advice.
It has carbohydrate counting software installed on the meter. Therefore, you can set your ratios into the sensor and use it as you would a smart meter.
Cons of the sensor
The big one is the cost. The cost of £50 per sensor has priced many patients out of funding one. Hopefully the cost will begin to drop as more companies produce rival sensors.
Some patients do not like the idea of having a sensor on their arm and choose to not use one for this reason.
Another major con is the sensors lag time behind blood glucose levels. This is particularly important around hypo’s because the sensor may provide a reading of 4mmol/l when in reality your levels are on their way to below 3mmol/l.
Glucose values taken from the sensor are not recommended to be used for carbohydrate counting because of the lag time compared to blood glucose values. Testing blood glucose levels for this remains the recommended method. Blood glucose levels can still be entered into the Libre sensor meter for calculations however.
Finally, and arguably the most important, the DVLA do not currently recognise Libre readings prior to and during driving. Blood glucose levels remain the only recognised values for driving. Not testing blood glucose levels for driving can result in legal proceedings.
It’s an exciting time for new diabetes technologies. Although still not easy, there’s never been a better time to manage your diabetes. The Libre appears to be an excellent tool for glucose level interpretation and help individuals test more frequently.
It does have some cons but in the grand scheme the Libre certainly appears to be a great tool for those individuals with diabetes.