How common is plasma measurement for glucose used? From what i read today it is 14% higher than a blood measurement. To add to the confusion, some blood glucometers are adjusted to match a plasma glucose value.
Indeed it is a problem that was more prevalent in days gone bye, Most meters in the UK that are CE marked and meet the ISO standard have been calibrated to give plasma equivalent readings so that the results are a closer match to the YSI Analysers used in the laboratories for official blood tests as required by GP or hospitals etc. The older whole blood or capilliary calibration is being phased out. Check the leaflet in the test strip box to find out what they are set to.
Even an ISO meter will have an error tolerance of +/- 15% so doing a back to back parallel test on the same drop can give a 30% variance and still be considered accurate.
My Abbott Neo and XCEED meters are both whole blood calibrated, ad my SD Codefree is plasma calibrated, There is a consistent 0.8 mmol/l difference between them with the Codefree being the higher over a period of 2 years, I almost never saw a reading where the Codefree read below an Abbott meter, and if I did it was usually a bum reading.
My confusion at the moment is that my new Spirit Dual is also reading like the Abbotts, but declares it is a plasma one too. Again there is a consistent 1.0 mmol/l difference between the sets of results. However, my HbA1c last week represents a 7.0 mmol/l daily average which is Exactly what the Codefree average was over the last 4 months. So the only meter I have that agrees with the lab is my old Codefree. Unfortunately, there are many anecdotal reports on this forum that the Codefree tends to read high compared to other meters, so I am not the only one experiencing this.
The only time I need an accurate reading is when I am close to hypo territory, and am testing before I drive to meet DVLA guidelines. (<= 3.9 mmol/l). Generally I use averages and trend analysis and not single readings.
