49
You may still have a variation from the result because blood glucose levels can change significantly over short
periods of time, especially if you have recently eaten, exercised, taken medication or experienced stress*2.
In addition, if you have eaten recently, the blood glucose level from a finger prick can be up to 70 mg/dL (3.9
mmol/L) higher than blood drawn from a vein (venous sample) used for a lab test*3. Therefore, it is best to fast
for eight hours before doing comparison tests. Factors such as the amount of red blood cells in the blood (a
high or low hematocrit) or the loss of body fluid (dehydration) may also cause a meter result to be different from
a laboratory result.
References
*2: Surwit, R.S., and Feinglos, M.N.: Diabetes Forecast (1988), April, 49-51.
*3: Sacks, D.B.: “Carbohydrates. “ Burtis, C.A., and Ashwood, E.R.( ed.), Tietz Textbook of Clinical Chemistry. Philadelphia: W.B. Saunders Com-
pany (1994), 959.
