Modeling Blood Glucose and Insulin Kinetics in Normal, Diabetic and Obese Subjects

A two-compartment model (figure 1) and digital computer technics have been applied to the analysis of glucose and insulin control mechanisms in twenty-six normal, sixteen diabetic, and eight obese subjects. The system was perturbed by infusing glucose (0.5 gm./min. for about 300 minutes) into the three groups or by injecting glucose intravenously as an impulse of 0.33 gm./kg.; plasma insulin and glucose levels were determined and the model was solved by simultaneously fitting to it the experimental data for glucose and insulin, and the additional information gathered by determining the blood disappearance curve of intravenously injected C-14-glucose. A discriminant analysis for two groups gave a statistically significant separation between normal and diabetic subjects (with infused or impulsive glucose) and between normal and obese subjects (with infused glucose) on the grounds of the seven parameters that characterize the model. The prominent feature of the diabetics (in addition to the obvious hyperglycemia) was a decrease of λ21 (figure 1), a parameter which measures the insulin response to a glucose load. The prominent feature of the obese subjects was an increase of λ21 and a decrease of —λ21, a parameter which measures the glucose response to insulin. These dynamic characteristics are in agreement with present knowledge of the impairment of glucose and insulin control mechanisms in these pathologic states.