Why continuous glucose monitors do not access blood?

[Rabdos]

Why continuous glucose monitors do not access blood?

Why they work on interstitial fluid only and not capillary blood?

 

[miahara]

Will be interested in any answers to your question @Rabdos . I'm quite glad the cannula on my Libre isn't long enough to draw capillary blood (ouch!).
I've found that there is only about a 1mmol difference beween a finger prick result and an interstitial reading.

 

[LittleGreyCat]

Easier to just stick it in than have to find (and keep contact with) a blood vessel?

There are posts by people who have hit real blood.
Some had to remove the sensor because of the flow, others said that it seemed to read better.

 

[LooperCat]

While they do occasionally hit a small blood vessel, it would be impossible to get one every time. And if clots form around the filament, the reading wouldn’t be accurate.

 

[Seacrow]

As a guess, because blood clots. When I have a cannula into a vein, after about half an hour the blood in the tubing has turned into a jelly-like 'worm', which would be useless for testing.

 

[Rabdos]

Okay I thought they had already solved the clotting challenge as we are implanting pacemakers and other devices without risk (not sure if you need to take blood thinners for life though).

 

[Struma]

Okay I thought they had already solved the clotting challenge as we are implanting pacemakers and other devices without risk (not sure if you need to take blood thinners for life though).

No you don't.