I am using the Abbott Libre Freestyle 3 as I have often noted herein, and paying for the same out-of-pocket. Recently I had a bad sensor, called Abbott’s customer service, and they replaced it and requested I send the defunct one back which I immediately did. Today I received a formal letter from Abbott which stated they had not received the return and requested the same. The letter went on to state if it had already been returned to disregard their request. Before the letter went in the bin I read the small print.
On the back of the letter under Warnings/limitations, it states: ” The FreeStyle Libre Pro System does not provide real-time results and patients should adhere to their blood glucose monitoring routine while using the system….Patients with high levels of ascorbic acid (Vitamin C) or salicylic acid (used in Aspirin) or severe dehydration or excessive water loss may experience inaccurate results with this system. The FreeStyle Libre Pro System is not approved for pregnant women, persons on dialysis, or recommended for critically ill population….” All emphasis is mine.
The first sentence, “patients should adhere to their blood glucose monitoring routine while using the system” directly states to keep doing old fashion finger pricks while using the Libre system. Doesn’t this totally beg the issue of why even use it then?
The second group excludes Orange Juice which I am drinking for breakfast since my dialysis dietician took me off tomato juice because of potassium, and I have also been taking glasses of orange juice to stave off low glucose readings. I take a baby aspirin every day to appease my cardiologist. I have noted that I have been receiving lots of low glucose readings from my Libre 3 while at the same time having no physical presence of being low. Having been at this game for about 40 years I know what a low feels like.
The last statement precludes persons on dialysis from using their CGM in no uncertain terms, no ifs ands, or buts.
I turned to my ChatGPT AI with the following prompt and response in an attempt to dig deeper into this subject with the following results:
Prompt: I just received a letter from Abbott concerning the use of the Libre 3 CGM system. It states in Warnings/Limitations that the Freestyle Pro system is not approved for persons on dialysis or with high levels of ascorbic acid (Vitamin C). Why is this?
ChatGPT provided the following response:
The Freestyle Libre 3 Continuous Glucose Monitoring (CGM) system, like many glucose monitors, works by measuring the level of glucose in your interstitial fluid. This is the fluid that surrounds the cells of your tissues, and it generally mirrors the glucose levels in your blood.
For people on dialysis, there could be a few reasons why the device isn’t approved. The body’s fluid levels can fluctuate significantly during dialysis, and this might affect the accuracy of the CGM system. Additionally, dialysis patients often have other health complications that might affect the system’s performance. However, without more specific information from the manufacturer, it’s difficult to say for sure.
As for high levels of ascorbic acid (Vitamin C), this is likely due to the fact that ascorbic acid can interfere with glucose monitoring systems. Many glucose monitors, including the Freestyle Libre, use a method called glucose oxidase to measure glucose levels. However, ascorbic acid can react with glucose oxidase, leading to falsely high glucose readings. This is a known issue with many glucose monitors, and it’s likely the reason why the Freestyle Libre 3 isn’t approved for use in people with high ascorbic acid levels.
At this point, I am flummoxed and speechless. No MD I have interfaced with has brought this up. No RN I have interfaced with has brought this up. No medical professional of ANY ilk has brought this up. I am going to continue underway as before and keep gathering data, such as it is. Stand by for another itshay!
I will await your conclusion on this one: unreal!