A generalized equation of oscillations is proposed in the language of the rate of of the oscillation system return to the equilibrium state, in which not only the inverse negative relationship of the integral character, that leads to harmonic oscillations, is taken into account, but also the inverse negative relationship of the local form with the delay. This equation is applied in the construction of the functional model of the system of self-regulation of the glycemia level, for which a parametric identification based on the reference glycemic data of glucose-tolerance tests was carried out