Abstract: A system for predicting a blood glucose level is comprised of a time series measurement data storing section for storing blood glucose level measured data in a blood glucose time series file to treat the data as time series data. A dynamics estimating section estimates a dynamics which most preferably represents a phase characteristic of the time series data stored in the time series measurement data storing section. A parameter storing section stores an embedding dimension n and a time delay .tau. of the dynamics estimated in the dynamics estimating section as parameters for embedding the estimated dynamics in multidimensional state space. A blood glucose predicting section predicts a near future value of blood glucose level by means of the Local Fuzzy Reconstruction Method on the basis of the stored data of the blood glucose level data stored in the blood glucose time series file and the parameters corresponding to the data and for storing the predicted future value in a predicted blood glucose level file.