Weekly Insulin Becoming a Reality

Abstract

Insulin was first isolated in 1921 and developed as a therapeutic agent in the 1920s. The initial crude preparations were injected multiple times daily because of their short duration of action. Consequently, there were many attempts to develop insulin preparations with prolonged biological availability in the hope that less frequent once-daily administration would be feasible (1). A host of such preparations were introduced, including protamine insulin, protamine zinc insulin, surfen insulin, globin insulin, iso-insulin, isophane insulin (NPH), and insulin zinc suspensions (lente insulins) (1) (Fig. 1). The goal was mainly to reduce the number of injections and thus the patient burden. Yet, with the development of a radioimmunoassay for insulin (2), it became apparent that physiologic insulin secretion involved two components: meal-related insulin secretion with postprandial spikes and basal insulin secretion that remains relatively constant with some minor pulsatility (3). Subsequently, as modern insulin therapy evolved, facilitated by patient self-monitoring of blood glucose (4,5), it became apparent that the inherent peaks in basal insulin preparations, such as with the nonsoluble NPH or lente insulins, created risk of hypoglycemia, especially if the insulin vials were not correctly rolled to create a proper suspension. Moreover, these insulins did not have sufficiently long duration of action to be used once daily. Consequently, in addition to making them soluble, two of the goals in development of basal insulin analogs, such as insulin glargine and insulin detemir, were to eliminate insulin peaks and to prolong the action to approach 24 h (6,7). Second-generation basal insulin analogs, such as insulin degludec and insulin glargine U300, came with …