I'm coming back as promised to report on progress - such as it is. Here is the explanation I got from Roche. Remember, all I want to know is how inaccurate my BG readings might be. In response to the below explanation, I then asked them whether the errors to be expected for control solution in non-lab conditions should also be expected for BG readings.
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Thank you for contacting Accu-Chek.
Please be aware that performing a control test in your home environment cannot by compared to performing a control test in a laboratory, as the strict laboratory testing conditions are not met in the home environment. This means that achieving the target reading of 6.67 mmol/l is not possible. Due to these factors a target range has instead been calculated. This range takes into consideration the effects of temperature deviations and possible sources of contamination. The specific target range for the Accu-Chek Compact Plus control solution is printed on the peel-off label attached to the drum container.
I'm just following up my enquiry, as I am quite urgently needing to know how to interpret my meter readings. My question is:
Since, as you explained, the measurement of glucose in the control solution is inevitably subject to error because of non-laboratory conditions, is the same true of blood glucose measurement? For example, if 6.7 mmol./l control solution reads out at 8.1 mmol/l, as a result of non-laboratory conditions, might I expect a similar margin of error for blood glucose readings?
I am concerned because the hospital reading was 5.3 for FBG, while my meter read 6.6 at the same time (within twenty minutes either side of the hospital sample).