Methods, devices, and systems may use a kinetic model to determine physiological parameters related to the kinetics of red blood cell glycation, elimination, and generation. Such physiological parameters can be used, for example, to determine a more reliable calculated HbA1c. In another example, a method may comprise: receiving a plurality of glucose levels over a time period； receiving a glycated hemoglobin (HbA1c) level corresponding to an end of the time period； determining at least one physiological parameter selected from the group consisting of: a red blood cell glycation rate constant (kgly), a red blood cell generation rate constant (kgen), a red blood cell elimination constant (kage), and an apparent glycation constant (K), based on (1) the plurality of glucose levels and (2) the HbA1c level； and adjusting a glucose level target based on the at least one physiological parameter.
