In this paper, the system of glucose regulation in a human body is discussed. Nonlinear Bergman’s minimal model representing this system is taken, and converted to fractional-order model using the Caputo definition. After that, method of feedback linearization is put forward for fractional-order nonlinear systems, and then applied to design observer based controller for an artificial pancreas for a patient with diabetes. Using FOTF toolbox in MATLAB, the designed controller, observer, and the system are simulated. Using simulation results, it is shown that the designed controller and observer are stable, and the desired level of glucose concentration is being tracked faithfully.