Future therapy of the insulin-dependent diabetic patient--the implantable insulin delivery system.

Abstract

An implantable insulin delivery system has several advantages not shared by currently available, portable external delivery devices. First, since the implantable system does not come in contact with the external environment, insulin delivery routes other than the subcutaneous tissue may be utilized without the danger of infection. These alternative routes may provide more rapid insulin absorption, enhanced hepatic insulinization, and improved diabetic control for “C”-peptide-negative brittle diabetic patients. Second, the implantable system is protected from external trauma, permitting a wider range of daily activities and sporting events. Third, the implantable system is easily concealed by clothing, thereby increasing patient acceptance of it. However, an implantable system also has disadvantages. First, surgery will be required to implant or explant the pump module and reservoir, and second, the implanted system must be highly reliable and include failsafe mechanisms to insure the safety of the recipient. These advantages and disadvantages have resulted in delineation of general specifications for an inv plantable insulin delivery system. Desirable features of an implantable insulin delivery system include (1) reliability and failsafe operation, (2) being implantable and explantable under local anesthesia, (3) long battery life, (4) multiple insulin delivery rates, (5) small size and weight, (6) biocompatible materials, (7) remote programmability based upon recipient blood glucose monitoring, and (8) ability to deliver concentrated insulin with infrequent reservoir refilling. Using available technology, each of these specifications has been incorporated into the functioning of our current implant system, which is being tested in diabetic dogs. Future experiments in man will undoubtedly alter and add to the current specifications.