An automated system for controlling a patient's blood glucose, comprising a processing and control unit capable of predicting, based on a first mathematical model, the future trend of the patient's blood glucose G(t) over a prediction period, wherein the first model takes as inputs: a variable EE(t) representative of the time variation of the patient's energy expenditure; a variable IOB(t) representative of the time variation of the patient's quantity of insulin on board; and a variable COB(t) representative of the time variation of the patient's quantity of carbohydrate on board, and wherein the first mathematical model is a model of black box type, that is, a non-physiological model only defined by the observation of the effects of input variables EE(t), IOB(t) and COB(t) on output variable G(t), without taking into account the different known physiological mechanisms operating in the patient's body, wherein, in operation, the control and processing unit receives a signal CHO(t), representative of the time variation of the quantity of carbohydrates ingested by the patient, and a signal I(t) representative of the time variation of the quantity of insulin injected to the patient, and wherein the control and processing unit is configured to calculate the input variables IOB(t) and COB(t) of the first model as follows: IOB t = ∑ k = 0 K I t − k ∗ h IOB k, and COB t = ∑ k = 0 K CHO t − k ∗ h COB k, where K is an integer greater than 1, k is an integer in the range from 0 to K, h IOB is an action function representing the time variation of the effect of the injected insulin on the absorption of blood glucose, and h COB is an action function representing the time variation of the effect of the ingested carbohydrates on the blood glucose. a variable EE(t) representative of the time variation of the patient's energy expenditure; a variable IOB(t) representative of the time variation of the patient's quantity of insulin on board; and a variable COB(t) representative of the time variation of the patient's quantity of carbohydrate on board, and wherein the first mathematical model is a model of black box type, that is, a non-physiological model only defined by the observation of the effects of input variables EE(t), IOB(t) and COB(t) on output variable G(t), without taking into account the different known physiological mechanisms operating in the patient's body, wherein, in operation, the control and processing unit receives a signal CHO(t), representative of the time variation of the quantity of carbohydrates ingested by the patient, and a signal I(t) representative of the time variation of the quantity of insulin injected to the patient, and wherein the control and processing unit is configured to calculate the input variables IOB(t) and COB(t) of the first model as follows: IOB t = ∑ k = 0 K I t − k ∗ h IOB k, and COB t = ∑ k = 0 K CHO t − k ∗ h COB k, where K is an integer greater than 1, k is an integer in the range from 0 to K, h IOB is an action function representing the time variation of the effect of the injected insulin on the absorption of blood glucose, and h COB is an action function representing the time variation of the effect of the ingested carbohydrates on the blood glucose.