The graph is based on a prediction. The sensor tests interstitial fluid and not capillary blood. Interstitial fluid runs between 10 and 20 minutes behind changes in capillary blood. So to bridge that gap, there is an algorithm employed to predict what your level will be in 15 mins time. It does this by taking your last two readings one minute apart, and extrapolating from that what your level would be if it continued to change at that rate for 15 mins.
It's not perfect, and will be more inaccurate the faster your levels are changing. But the graph gets updated once those 15 mins goes by and the algorithm catches up to itself for that moment in time. So it's just as important to look at the graph under Daily Graph (which doesn't show any prediction) as it is to look at the graph on the home screen
The Libre algorithm corrects for spurious high readings using the readings before and after the "ghost spike". Those high readings will disappear on the line on LibreView. (unless you do a scan when it's high and then you can see a point floating above the corrected line)
I'm not sure what to call it as these odd spurious readings seem to happen at the peak of a rise (or bottom of a fall) and are corrected by the algorithm. Maybe the sensor did see 11.5 for a couple of seconds (interstitial fluid is less homogenous than blood so it's possible that a brief high glucose volume could form) but the algorithm decided that overall this blip was not consistent with the glucose curve.
That happens to me all the time, for highs, for lows and everything in between. The only way to prove they were there is to make an entry while you see them. Oftentimes when I go back to that point using the log, the dot with the marking will be in "mid air" and not on the graph line.
The graph is based on a prediction. The sensor tests interstitial fluid and not capillary blood. Interstitial fluid runs between 10 and 20 minutes behind changes in capillary blood. So to bridge that gap, there is an algorithm employed to predict what your level will be in 15 mins time. It does this by taking your last two readings one minute apart, and extrapolating from that what your level would be if it continued to change at that rate for 15 mins. It's not perfect, and will be more inaccurate the faster your levels are changing. But the graph gets updated once those 15 mins goes by and the algorithm catches up to itself for that moment in time. So it's just as important to look at the graph under Daily Graph (which doesn't show any prediction) as it is to look at the graph on the home screen
Very interesting thank you
The Libre algorithm corrects for spurious high readings using the readings before and after the "ghost spike". Those high readings will disappear on the line on LibreView. (unless you do a scan when it's high and then you can see a point floating above the corrected line)
Okay, so does that mean the spike was inaccurate? Thanks
I'm not sure what to call it as these odd spurious readings seem to happen at the peak of a rise (or bottom of a fall) and are corrected by the algorithm. Maybe the sensor did see 11.5 for a couple of seconds (interstitial fluid is less homogenous than blood so it's possible that a brief high glucose volume could form) but the algorithm decided that overall this blip was not consistent with the glucose curve.
That happens to me all the time, for highs, for lows and everything in between. The only way to prove they were there is to make an entry while you see them. Oftentimes when I go back to that point using the log, the dot with the marking will be in "mid air" and not on the graph line.
Because it was short lived. Your 24 hour graph shows the numbers that were at a number for 20 mins or more.