Modelling the effect of CSII on the control of glucose concentration in type 1 diabetes

The profile of insulin release in continuous subcutaneous insulin infusion (CSII) plays a major role in regulating blood glucose in type 1 diabetes. We develop a mathematical model to incorporate the effect of an intermittent insulin supply on glucose concentration, as a function of time for the dual wave bolus technique. The rate of exogenous insulin release is controlled by a threshold of glucose concentration, determined by the characteristics of the patient's body. The results of model simulations provide the optimal profile of insulin release over a specific period of time. Only marginal decrease in the time required for lowering blood glucose level is observed when the total daily dosage (TDD) is greatly increased. This may also be of less benefit in terms of the amount of insulin secreted in the body and will in turn lead to a glucose level outside the physiological range, due to a delay in the glucose metabolism. We also analyze the model to determine the conditions under which oscillatory dynamics of glucose concentration can be observed. Consistent with other modelling studies, the results suggest that an oscillatory insulin supply will be more efficient in producing a sustained physiological response than a constant supply.