Computer simulation of plasma insulin and glucose dynamics after subcutaneous insulin injection.

We developed a computer program for the simulation of plasma insulin and glucose dynamics after subcutaneous injection of insulin. The program incorporates a pharmacokinetic model to calculate the time courses of plasma insulin for various combinations of popular preparations (regular, NPH, lente, and ultralente). With the use of a pharmacodynamic model describing the dependence of glucose dynamics on plasma insulin and glucose levels, the program can predict the expected time course of plasma glucose in response to a change in carbohydrate intake, insulin dose, timing, or regimen. A set of typical parameters has been obtained by analysis of data from the literature. The results of several computer simulations are presented showing the effect on a 24-h insulin and glucose profile of systematically changing insulin regimen, dose, timing of meals, or timing of preprandial insulin administration. The program can be used to explore on a theoretical basis the impact of various factors associated with glycemic control in insulin-dependent diabetes mellitus. As an educational tool, the program provides a realistic environment for demonstration of the combined or isolated effects of insulin and diet on glycemia.