A new approach is proposed in the paper for unknown glucose inlet estimation in case of diabetic patients under insensitive care in form of a Linear Parameter Varying (LPV) model class. The nonlinear two compartment glucose-insulin system is rewritten in affine parameter varying form in order to handle the dynamics with LPV Fault Detection and Isolation (FDI) method. The aim of the closed-loop fault detection, on the one hand, is to estimate the unknown disturbance input of the system, on the other hand to recognize the actuator fault. A parameter varying controller assures the performance requirements and stability of the system.