In this study, a closed-loop system to control the plasma glucose level in patients with diabetes mellitus type 1 is proposed. This control scheme is based on fuzzy logic control theory to maintain a normoglycaemic average of 4.5 mmol 1(-1) and the normal conditions for free plasma insulin concentration in severe initial state; in particular, when the diabetic patient is subjected to a glucose meal disturbance or fluctuations in the measured glucose level due to error in the measuring instrument. The proposed controller has demonstrated superiority over other conventional controlling therapies. While fuzzy logic controllers have shown promising results in many fields, a comparative study is presented with well-known conventional controllers such as Proportional-Integral-Derivative (PID) and continuous insulin infusion control strategies. The simulated results, for the proposed controller, are presented and discussed.