Measurement of glucose in an insulin delivery catheter by minimizing the adverse effects of insulin preservatives

Abstract

This disclosure teaches the concept, and method of creating, a dual use device intended for persons who take insulin. In one embodiment, the novel device is an insulin delivery cannula, the outer wall of which contains electrodes, chemical compounds and electrical interconnects that allow continuous glucose sensing and delivery of data to a remote device. Heretofore, the main problem in attempting to sense glucose at the site of insulin delivery has been the high current resulting from oxidation by the sensor of the preservatives in the insulin formulations. One means of eliminating these interferences is to poise the indicating electrode(s) of the sensor at a bias sufficiently low to avoid the signal from oxidation of the preservatives. One way of obtaining a glucose signal at a low bias is to use an osmium-ligand-polymer complex instead of conventional hydrogen peroxide sensing. Another is to use a size exclusion filter located in line with the insulin delivery tubing in order to remove the smaller phenolic preservative molecules while allowing the larger insulin molecules to pass unimpeded. These filtration concepts can also be more broadly applied, that is, the general concept of removal of unwanted drug formulation excipients from a drug delivery system.