Normalization of Insulin Delivery to Diabetics by Pulsed Insulin Infusion

The objective was to continuously provide insulin to diabetic patients so as to mimic the time course of natural plasma insulin in response to meal ingestion in normal subjects. The normal curve of plasma insulin was well approximated as a double exponential, and this function was used as the output of a mathematical model of the body compartment plasma insulin-clearance system in order to derive an input expression. This input expression was thus the infusion time function needed to produce the desired plasma time function of insulin concentration in diabetics. The infusion function was implemented with a special purpose computer, designed with logic technics, that was then used to drive a servo infusion pump. The system delivered a 4-5-h pulse of insulin, the parameters of which were tailored for each patient's body weight and clearance rate, and with the different required profile for each of the three daily meals. These pulses rode on top of a constant basal infusion rate, the basal rate being delivered only throughout the night hours. The system was successfully tested on a simulated (hydraulic) patient, and then on one of us as a human volunteer., It has since been used with 10 diabetic patients in which the original objective was accomplished with satisfactory clinical results.