Transition from 12 to near-24 hours glucose circadian rhythm on   relaxation of a hyperglycemic condition
  A composite, exponential relaxation function, modulated by a periodic component, was used to fit to an experimental time series of blood glucose levels. The 11 parameters function that allows for the detection of a possible rhythm transition was fitted to the experimental time series using a genetic algorithm. It has been found that the relaxation from a hyperglycemic condition following a change in the anti-diabetic treatment, can be characterized by a change from an initial 12 hours ultradian rhythm to a near-24 hours circadian rhythm. 
Baruch Vainas