A pre-programmed controller that works over a family of single-input single-output systems representing the diabetic subject was achieved, based on the recent practical fourth-order digital model of the experimentally validated glucoregulatory system. The controller was chosen such that it contains an integral action to ensure that the steady-state error vanishes. Its zeros are so selected as to match the undesired complex-conjugate poles of the unstable metabolism. The controller utilizes a nonlinear reference: ramp function succeeded by step input. The closed-loop gain and the coefficient of the ramp function are tuned successively such that desired dynamics are obtained using the root-locus portrait. Three sets of well-behaved responses and their corresponding internal states were obtained with variable peak undershoot. The robustness tracking property of the controller was tested using the bounding polynomials suggested by Kharitonov's stability criterion.