People with diabetes have been delighted to have an alternative to fingerstick testing for blood glucose self-monitoring, with new devices that can use samples from other sites such as the forearm and thigh. And these devices have been approved as providing accurate readings of blood glucose.

However, two new studies caution about the readings obtained from such samples at a time when blood glucose levels are changing rapidly.

• German researchers reported that the blood glucose values at the fingertip and forearm were similar during the fasting state. However, the measurements at the fingertip were consistently higher during rapid increases in glucose, such as after a meal. The blood glucose concentration from the arm sample was delayed by a median of 35 minutes in relation to that obtained from the finger. They also found that rubbing the skin of the forearm before sampling did not reliably improve the accuracy of the readings from that location.

• Researchers at LifeScan found that changes in blood glucose immediately after a meal may be identified at finger sites before they may be detected at forearm or thigh sites. Readings from the alternate sites were lower than finger readings at 60 and 90 minutes after a meal.

Thus, it appears that alternate site testing is OK for routine self-monitoring before meals, but patients should be aware that after-meal testing might not be as accurate from those sites.

Related information: Latest developments - technology | Glucose control - blood tests

Sources:

• Jungheim K, Koschinsky T. Glucose monitoring at the arm: risky delays of hypoglycemia and hyperglycemia detection. Diabetes Care, June 2002;25:956-960. (Abs.)
• Ellison JM, Stegmann JM, Colner SL, et al. Rapid changes in postprandial blood glucose produce concentration differences at finger, forearm, and thigh sampling sites. Diabetes Care, June 2002;25:961-964. (Abs.)