Blood sugar discrepancies
Many of my diabetic patients see a difference (as much as 15-20 mg/dL) in their blood glucose when samples are taken from different parts of the body. Do you have any suggestions for those who don't like finger sticks?
—G. Tadros, MD, Wilmington, Del.
The discomfort of finger sticks has prompted the development of various glucometers that allow a patient to obtain a blood sample from alternate testing sites. One study found a glucometer that tests blood samples from the arm to be just as accurate as and less painful than finger-stick testing (Diabetes Care. 2001;24:1217-1220). However, there can be variability between different testing sites if the sample contains venous blood rather than the capillary blood sampled from the fingertip; this may account for the difference your patients are reporting. Similarly, when the blood glucose is changing rapidly, there may be a delay in the measured rise and fall of blood glucose obtained from alternate testing sites in comparison with finger-stick testing (Diabetes Care. 2002;25:961-964). I would suggest that patients who dislike finger-stick testing consistently use the same alternate testing site for routine monitoring but use finger-stick testing if the test is done shortly after a meal or if they are having symptoms of hyperglycemia or hypoglycemia.
—Daniel G. Tobin, MD (121-8)