Some glucose meters allow testing blood from alternative sites, such as the upper arm, forearm, base of the thumb, and thigh. Sampling blood from alternative sites may be desirable, but it may have some limitations. Blood in the fingertips show changes in glucose levels more quickly than blood in other parts of the body. This means that alternative site test results may be different from fingertip test results not because of the meter’s ability to test accurately, but because the actual glucose concentration can be different. FDA believes that further research is needed to better understand these differences in test values and their possible impact on the health of people with diabetes.