Infusion systems, infusion devices, and related operating methods are provided. An exemplary method of operating an infusion device involves obtaining a filtered measurement indicative of a physiological condition of a user, determining a metric indicative of a characteristic of the filtered measurement based at least in part on one or more derivative metrics associated with the filtered measurement, and determining an output measurement indicative of the physiological condition of the user based at least in part on the filtered measurement, the metric, and a previous output measurement.