A mathematical insulin-secretion model was constructed by analyzing the glucose-induced insulin secretion using a control theory. To validate the model, experimental data obtained in the isolated rat pancreatic islet perifusion system were compared with the simulation results. The simulation study of the model was found to fit quite well to insulin responses under various experimental conditions. A glucose-induced insulin secretion from pancreatic islets' beta cell was found to be expressed as a function of proportional plus derivative response to glucose input with the first order time lag. And the negative rate of change in glucose concentration was found to suppress insulin secretion to the extent of the negative stimuli, regardless of glucose concentration. This model would be useful as a research tool for analysis of physiological significance of insulin secretory dynamics and clinical investigation of insulin secretion.