If your son's diabetes is considered a disability under the ADA, you might want to talk with EEOC or your state equivalent to see if your employer's treatment is consistent with the association provisions of the ADA. Of interest, is why your employer didn't give you the opportunity to select a schedule as other employees were allowed to do. An employer doesn't have to provide you with a reasonable accommodation because of the needs of your disabled child, but it can't treated you differently than other similarly situated employees because you have a disabled child. See http://www.eeoc.gov/facts/association_ada.html.