A process for calibrating a glucose sensor under sterile conditions includes providing separate, sterile, glucose-containing calibration fluids, each having a different glucose concentration, and in turn providing these fluids to a sensing zone containing a sensing probe of a glucose sensor. Each solution is typically, in turn, propelled into the sensing zone, thus flushing out used fluid already present in the sensing zone. The process provides rapid calibration of a glucose sensor in a sterile fashion and is therefore appropriate for point-of-use calibration.