FFT analysis and periodic function regression of glycemia time fluctuations in diabetes

Fast Fourier transform (FFT) and periodic function regression (PFR) have been used to analyze time fluctuations of blood glucose in hospitalized patients with insulin and non-insulin dependent diabetes mellitus (IDDM and NIDDM, respectively), PER outlined oscillations around 6 h, 1 wk and 1 mo, similar in IDDM and NIDDM. FFT disclosed a more complex: periodicity of glycemia. In spite of high individual specificity, power spectra evidenced 14 oscillations common to both IDDM and NIDDM (periods from 7.3 h to 5.2 d including a circadian rhythm of 24.5/spl plusmn/0.9 h). Rhythms specific to each type of diabetes were observed ground half a day (IDDM: 11.45/spl plusmn/0.05 h, NIDDM: 12.4/spl plusmn/0.3 h, p<0.005), and at 28.7/spl plusmn/0.1 h only in NIDDM. Feed-back mechanisms in a multi-compartment model involving impaired insulin and counter-regulation hormones may account for multiple glycemia periodicity. Possible clinical applications are suggested.