You have not indicated which particular method was used in testing your blood sugar.I assume it was using a glucometer.
As per ISO 15197 standards, glucometers must provide results that are within 20% of a laboratory standard 95% of the time for concentrations about 75 mg/dL. For lower levels of blood sugar, they should approximate the 'absolute'(100%) laboratory standard levels.
It is extremely important that at blood sugar values around the lower limit of the laboratory normal range,the glucometer should deliver accurate values. This is crucial in type 1 diabetics taking insulin. Unfortunately, all glucometers may not be accurate enough at the lower blood sugar levels.
Some of the factors affecting the accuracy of glucometers:
- calibration of the meter,
- dirt on the instrument,
- ambient temperature(sampling capillary blood from a finger or a heel that is too cold, can give a falsely-low blood sugar readings),
- humidity levels,
- size and quality of blood sample,
- pressure use to wipe off the test strip(if applicable),
- high blood levels of certain substances (ex; ascorbic acid),
- hematocrit of thesample,
- shelf life of the strips,
- slight delays in transferring the blood sample to the meter (blood that has begun to clot may yield very low readings) etc.
Therefore, i suggest that you should have your blood sugar values checked in a laboratory and look for a correlation with your symptoms.
MB BS, MS, FRCS(Edinburgh)