A simulation model for glucose kinetics and estimates of glucose utilization rate in type 1 diabetic patients

A glucose kinetic model is described that contains insulin-independent and insulin-dependent pathways of glucose uptake and includes a saturating flux term for glucose transport into the cells by the glucose transporters. The rate of glucose utilization was estimated in control subjects and diabetic patients by use of a bolus of [3-3H]glucose. Diabetic patients were studied after three regimens of insulin therapy: 1) after 24 h of insulin withdrawal, 2) after conventional insulin therapy, and 3) after an overnight insulin infusion such that plasma glucose was maintained between 4 and 6 mmol/l. In addition, the model was used to simulate published results from glucose clamp experiments with a range of glycemic levels and insulin concentrations. Estimates of glucose utilization flux in diabetic patients and model simulation suggest that high plasma glucose concentrations in uncontrolled diabetic patients can be attributed to a high glucose production rate by the liver associated with a reduction in glucose metabolic clearance rate due to relative saturation of the available pool of glucose transporters.