I think a lot of people believe it can alter the readings but there are studies that show otherwise.
Simply experiment for your self and then decide if it's ok or not.
"In our study, use of an instant hand sanitizer was compatible with the results of a blood glucose monitor and did not affect finger stick blood glucose results. However, depending on surface area, hand sanitizers may not be adequate for cleaning the skin prior to glucose meter testing."
" Therefore, when used according to manufacturer’s instructions, the data suggest that alcohol-based hand sanitizers are compatible with the OneTouch Ultra2 blood glucose monitoring system, and hand sanitizer does not cross react or otherwise interfere with test strip chemistry or glucose meter results"
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3262711/