: Diabetes is one of the most serious, rampant and costly endocrine disease in the world that requires artificial control and regulation of blood glucose concentration level. The latest World Health Organization report has predicted an increase of the adult diabetic population from 4% (180 million) in 2008 to 4.5% (350 million) in 2030. Meanwhile, Iran has currently allocated almost 7 million (8.9 percent) people suffering from diabetes. Diabetes is a metabolic disorder of the body which is mainly divided into two types including, type I diabetes and type II diabetes. In type I diabetes, autoimmune reaction of the body results in destroying ? cells in the pancreas preventing it to create insulin. In type II diabetes, the person develops a resistance to insulin. In general, in any type of diabetes, the cellular system cannot convert carbohydrates into the energy required by the body, eventuating in the high blood glucose concentration (higher than 180 mg/dl) or hyperglycemia . High blood glucose concentration for a long period of time leads to some chronic complications, including cardiovascular diseases, kidney failure, blindness, stroke and non-traumatic limb amputation. On the contrary, low blood glucose level (lower than 60 mg/dl) or hypoglycemia, caused by high dose of injected insulin, can cause loss of consciousness, coma and even death. According to aforementioned reasons, tight control of blood glucose level in type I diabetics is of great importance and in the recent few decades, extensive research has been done in this field. This thesis attempts to present a suitable controller for controlling the blood glucose concentration level in type I diabetics according to the selected model for the glucose – insulin system. To this end, for designing the controller, first a nonlinear model of type I diabetic (minimal model) is considered. Then, in order to investigate the accuracy of the mentioned model for the glucose – insulin system, the model is simulated for different parameters and hypotheses presented in the different papers so that the correct values ??for the parameters will be considered. Then, feedback linearization controller for controlling the blood glucose concentration level is proposed and its stability is investigated. In order to demonstrate the capabilities of the controller, its performance against food disturbance and changing in the parameters is studied. Based on the obtained results, this controller has a good rate of convergence to glucose reference value and removes food disturbance well. Next, because of the good performance of the first-order and higher-order sliding mode controllers against non- modeled dynamics, in order to improve these methods and remove their chattering phenomenon, these two methods are combined with fuzzy logic, the result of which are two controllers including fuzzy high-order sliding controller and fuzzy first-order sliding mode controller. In order to demonstrate the capabilities of the mentioned controllers, their performance against food disturbance and changing in the parameters is studied. The simulation results show the ability of the proposed controllers to control the blood glucose concentration level and eliminates chattering phenomenon in the control signal. Key Words- Diabetes, Control of blood glucose concentration level, Feedback linearization controller, Fuzzy high-order sliding controller, Fuzzy first-order sliding mode controller