Do You Need Test Strips When Using Libre?

“An end to finger pricking!”

“Finally, no more painful finger pricks”

Freestyle Libre and CGMs are often marketed to people living with diabetes as a way to leave finger pricking and the endless use of test strips behind. Indeed, if you have a flash or continuous glucose monitor sensor attached to your body then why would you need to crack open the test strips and take a drop of blood from a finger?

You shouldn’t, in theory. The data given by your sensor should be enough for you to make effective decisions when managing your diabetes. Only this year did the DVLA deem that Libre data was enough to allow PWD to safely drive a car. So that’s it, right? You have Libre on your arm and you can forget about hurting your finger tips X amount of times per day.

Not exactly for some, it seems.

I recently had a couple of discussions in regards to test strips and finger pricking on Twitter. The variance in what different people use, in regards to test strips, is huge. That isn’t a big surprise. Your diabetes may vary and all that. What did surprise me was the differing amounts used by PWD (specifically T1D) who are using Libre. It ranged from zero to several hundred per month. Why would that be? If they are using Libre or a CGM then why are PWD still finger pricking and using test strips?

There seemed to be several different answers to that question. “Accuracy” was a word that cropped up several times. We know different blood glucose monitors will almost always show slightly different values. The same applies when comparing Libre to a finger prick. Libre values are delayed as they read glucose levels from interstitial fluid rather than blood. Interstitial fluid is the fluid that surrounds the cells of your tissue below your skin, and usually glucose moves from your blood vessels and capillaries first and then into your interstitial fluid. Therefore, Libre readings will always be slightly delayed compared to a drop of blood from your finger tip. That could explain some of the accuracy concerns from some users and one reason for finger pricking. Why else?

Feeling hypo or hyper have both been stated as reasons. A hypo is likely the most popular reason for finger pricking when you’re using a Libre. That situation is often more of an emergency and an accurate, up to date number seems the safe route to take.

As an example; Libre is reading 4.0 mmol/l, the trend arrow is pointing down, the drop is at the rate of 0.5 mmol/l every 5 minutes. That is usually the time a PWD will start to take on board carbohydrates (if not sooner if the trend was noticed). However, if Libre readings are delayed by approx 15 minutes the true blood glucose value could be as low as 2.5 mmol/l – A much more serious reading which might require more faster acting glucose to rectify.

It would seem, for many that finger pricking is still a necessity when using Libre even if the amount of finger pricks and test strips are reduced from pre-Libre use.

What is worrying is that some HCPs are restricting test strips to their patients after Libre has been prescribed.

“You don’t need that many”

“You shouldn’t be testing so much now you have Libre”

Those responses and other similar remarks are incorrect. You need as many test strips as you think are reasonable and SAFE for you to effectively manage your diabetes. Some PWD are entirely comfortable with the occasional finger prick and test strip because it works for their management. Others might be checking five or six times per day and at that rate they’ll need over 150 test strips per month.

Struggling to get the test strips you need? Recently, Professor Partha Kar has written to CCG Accountable Officers, CCG Clinical Leaders, Directors of Commissioning Operations & Regional Medical Directors. In that letter, Professor Kar wrote:

“We would also like to take this time to remind you of the relevant NICE guidelines setting out the importance of access to blood glucose test strips. We would expect to see a reduction in the use of strips for patients in receipt of flash glucose monitors, however they – and other people with Type 1 diabetes – should still be able to access them when required. For people without flash, NICE recommends strip usage of at least 4 and up to 10 times/day. 

“We encourage CCGs to continue to work with local clinicians to ensure appropriate numbers of test strips are made available. For more information see NICE guideline NG17: https://www.nice.org.uk/guidance/ng17. “

How many test strips you need, when using Libre, is very personal to you. We recommend that you work out the amount YOU require each month then discuss a comfortable prescribed amount with your HCP.

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