Insulin Delivery Systems: Do They Need a Glucose Sensor?

New systems are being developed for continuous insulin infusion in diabetes mellitus. Of these, the bedside closed-loop system (artificial B-cell) normalizes measured blood glucose in the fasting and fed states, while favorably altering other fuel substrates and hormone levels in short-term studies of 1–2 days. More recent portable, external open-loop insulin delivery systems have been developed which can be programmed to achieve similar results in long-term studies in animals and humans. This is accomplished without the need for continuous glucose sensing. The partial metabolic normalization achieved is not compromised by physical exercise, and unacceptably low blood glucose levels are rarely observed. Further development and application of these new systems will enable researchers to establish whether the achievement of ideal metabolic control in diabetes can be realized with or without sensors for glucose or other metabolites.