Experiences with the Freestyle Libre

We’ve been using the Freestyle Libre for just over a year now to help my daughter manage her Type-1 diabetes. I wanted to share a few thoughts about how well it’s been working for us. I had lots of questions at the start, so I wanted to help capture what we’ve learned in case its useful for anyone else.

I’m writing this as a parent, rather than as a person with experience of wearing a sensor or the emotional cost of dealing with diabetes. Do not take anything I write here as medical advice, this is just a summary of our experience with the sensors.

My daughter is now 13. It was her decision to trial the sensor and hers to continue its use.

Cost & Shipping

Firstly, the Libre is not currently available on the NHS. But I believe it’s under review. This means we’re paying for the sensor ourselves. We’re lucky enough to be able to afford that, but not everyone is able to do so.

To use the sensors you need a reader (£57.95) and then sensors. While the sensors are priced at £57.95 each this includes VAT. When completing an order, if you’re buying the sensor for yourself to help you manage your diabetes, or for a family member then you can fill in a disclaimer and the VAT is waived. For our last sensor order we paid £48.29 per sensor. Sensors last a maximum of 14 days (see below) so on average you will be paying around £24 a week.

Shipping is quick and you’ll pay around £5-6 for postage. We buy ours in packs of 5 as that covers around 10 weeks worth of usage and reduces postage costs.

When we first bought the sensors we bought a pack of 10. I wouldn’t advise this as the sensors do have a use-by date, so you can’t just stock up.

Lifetime

Once fitted a sensor lasts 14 days maximum. You can’t choose to wear it for longer: the reader will no longer collect data from a sensor 14 days after its been activated.

While we’ve had a full 14 days from many of the sensors, in some cases they may come off early. They’re pretty secure once fitted, and in the optimum location in the back of the upper arm they are generally out of the way. But we’ve also had a number that haven’t lasted that long. They can be knocked off. We’ve also had to put tape over some sensors that have started to come off the skin.

When travelling we generally take a spare as well as manual blood testing equipment. See below.

Fitting the sensor

Fitting the sensor is straight-forward. The arm is swabbed with an alcohol wipe to clean the skin, then the sensor is pushed into the arm using a single-use applicator that comes with each sensor. They can be fitted in a couple of minutes. After activation using the reader it takes an hour before the first readings are available.

The applicator makes a clunking sound as the sensor is injected into the skin. It’s a bit like using a hole punch. Martha occasionally has some pain and soreness but that passes quickly.

On one occasion I’ve had a sensor fail to attach properly. This was because I tried to apply the sensor too soon after using the alcohol wipe. I’d recommend letting the skin fully dry before application to ensure the sticky pad adheres properly.

You can shower and swim when wearing the sensor.

Travelling with the sensor

Travelling with diabetes isn’t easier. Airports aren’t generally welcoming to people carrying bags of needles and vials of liquid.

Our understanding is that the sensors won’t go through metal detectors, but might be OK for X-Rays. As a minimum you’ll need to inform security if you or a family member is wearing a sensor. As our daughter now also wears an insulin pump, on our last few flights we’ve ended up having to opt out of all scans. This involves some headaches as you might imagine, but staff in the UK and elsewhere have so far been very helpful.

There is probably better advice online. Our experience is relatively limited here.

Removing the sensor

The sensors are fairly easy to peel off and remove, although the glue takes some scrubbing off. There’s no needle in the device, just a hair-thin sensor. The applicators can go in the bin, but we put the sensors in our sharps bin.

Sometimes the skin under the sensor can be a bit inflamed, but we’ve not had any serious side effects or issues.

Taking readings

To collect readings from the sensor you just scan it with the Reader. It works through clothing, so very easy to do.

The sensor collects readings every 15 minutes automatically and stores up to 8 hours of readings. All of the stored readings are automatically downloaded to the Reader whenever you scan it.

If you have an NFC enabled phone then you can collect readings using the LibreLink app. There’s also a LinkUp app to share readings with family members.

How the sensor helps to manage diabetes

The sensor removes the need to do routine finger prick tests. Martha no longer has to take blood glucose readings before meals, we can just scan her sensor and then work out the necessary dose and any correction.

Now that she is also using an insulin pump its really just a matter of scanning and then entering the data into the pump. It will work out any necessary corrections. The combination of the sensor and the pump has made an incredible difference to the routines of managing diabetes. For the better.

However using the Libre doesn’t mean that you can give up finger pricks completely. The sensor has limited accuracy with blood glucose levels below 4 or above 14. Outside of those ranges you must still do a finger prick test to ensure that you have an accurate reading for treating hypo- or hyperglycemia.

Accuracy of the sensor

Our biggest challenge when starting to use the Libre was understanding its differences from routine finger prick tests. This made us very wary about its accuracy initially. I’ll try to explain why.

If you want a detailed review of the Libre’s accuracy, then you can read this scientific paper which summarises a controlled test of the Libre. It helps to demonstrate the accuracy and reliability of the sensors, but may be too detailed for some people.

When you perform a finger prick test you are directly measuring the amount of glucose in your blood. But the Libre isn’t testing your blood glucose. The Libre sensor is testing the fluid between the cells in your skin. That fluid is known as interstitial fluid.

Interstitial fluid, it’s nutrients and oxygen are replenished from your blood stream. This means that you’re only indirectly testing your blood glucose. It takes time for glucose to pass from your blood into the fluid. Roughly speaking a measurement from the sensor is around 5-10 minutes behind your actual blood glucose level. If you’re running low on the sensor, your blood glucose might be even lower. And vice versa.

This explains why you need to finger prick when you’re low or high: you need to be treating your actual levels. On a routine basis, this delay isn’t an issue. It’s only when you’re particularly low or high that you may need to be more vigilant. This also explains why you need to travel with a full set of equipment and not just replacement sensors.

While there are delays, the fact that the Libre is constantly recording means that whenever you scan you’re getting an updated graph of your glucose levels, not just a single reading. The Reader will show you the graph and also give you an ideal if you’re level, rising (or falling) slowly, or rising (or falling) rapidly. That makes a massive amount of difference.

When we started testing the Libre we were doing routine finger pricks as well. The end result was a bit like wearing several watches, each of which is showing a slightly different time. We felt like we wouldn’t be able to trust the sensor because it was so often at odds with the blood glucose readings. The fact that this was also happening at a time when Martha’s levels were particularly erratic didn’t help: with highly variable blood glucose levels, you can feel one step behind.

Once we committed to using the Libre as our means of routine testing, everything was fine. You just need to be aware of the differences. Martha’s HBA1C levels demonstrate that we’re able to efficiently manage her glucose levels.

One additional issue to be aware of is that it takes time for the sensors to bed in. A sensor won’t start reporting readings until after its been on the skin for an hour. But we, and others, have found that it can take some time after that before readings seems reliable. Some sensors seem to work fine straight away, others seem a bit variable.

We’ve not had an issue with a sensor never settling down, they’re normally fine after a few hours. But its often hard to tell: is it the sensor, or just a particularly variable set of glucose levels.

We’ve heard that some people using the Libre install a new sensor 24 hours before the previous one runs out, to allow time for it to settle in. We’ve not found it necessary to do that.

Conclusion

Type 1 diabetes is an incredibly difficult condition to live with. I have nothing but admiration for how well Martha is dealing with it. She is my hero.

The Libre has made a significant difference to her (and our) quality of life. Removing the need for routine use of needles greatly reduces the number of medical interventions we have to make every day. The ability to easily scan to get a reading of glucose levels makes it easier for Martha in all aspects of her daily life. It’s much less obtrusive than finger pricking.

As parents it’s easy for us to check on her levels when she’s sleeping. A quick scan is all it takes. An integrated sensor and pump might be even better, but the smaller size of the Libre sensors make it perfectly adequate for now.

I hope the Libre becomes more widely available on the NHS so that more people can benefit from it. I also hope this article has been useful. We’re very happy to answer any other questions. Leave a comment or drop me an email.