Today's diabetic, unlike Joe Gilchrist, has a broad range of insulin at his disposal.
In 1935, a group of scientists under H. C. Hagedorn in Copenhagen declared that they had the answer for the insulin problem—two answers, actually. With this, Denmark began a virtual monopoly on insulin discoveries.
The first discovery lengthened the action of insulin so that one injection could work around 12 to 16 hours. This increase was found by adding to the insulin a simple protein substance known as protamine, obtained from the sperm of the rainbow trout. The protamine connected itself to the insulin and made a slower release of insulin activity. This came to be called protamine insulin.
The second breakthrough was an extension of the first. Hagedorn found that by putting zinc to the protamine insulin, the action was prolonged even more and would last for more than 24 hours. Protamine zinc insulin, a whitish fluid, was made available in the United States in 1937. With the coming of the Danish-developed insulin, it was possible for most diabetics who demanded moderate doses to handle their ailment using only one injection a day.
But protamine zinc insulin was not a solution to all the problems. There were still several diabetics whose insulin needs were so complex that not one of the available insulins could give them the necessary protection with a single injection.
Children, for instance, need really rapid insulin activity. Regular and crystalline zinc insulins gave them the speed they required but didn't last long enough. Protamine zinc insulin, while it afforded prolonged activity, didn't start soon enough.
Other diabetics whose ailments were erratic determined that the protamine zinc insulin didn't give enough activity throughout the day, when they were eating. At nighttime, when the long-acting insulin had no food to work on, there would be excessive insulin action and the patient could go into shock. In the aspect of these special needs, blended insulins came into use for juvenile, insulin-deficient diabetics. Instructed by their doctors, the patients would make the mixtures using the hypodermic syringe, combining the needed quick-acting and the long-acting insulins to give them the type of activity they demanded.
These mixtures tested so useful, and their use became so widespread, that they led to the creation by Hagedorn of Neutral Protamine Hagedorn (NPH) insulin. This insulin resembles a mixture of three parts regular and two parts protamine zinc. It is a lot stable than the homemade mixtures, more predictable and has greater flexibility than the pure insulins that preceded it. NPH has established vitally important for children; and, for erratic diabetics, affords more activity throughout the day and less at night, thus alleviating the hazard of shock.
Two more insulins were still to arrive. One was globin insulin, which came out in 1943. This comprises of regular insulin to which globin, a protein from beef blood, is added up to slow the action. Like regular and crystalline zinc insulins, globin insulin is a colorless fluid. It has a long action and a much slower onset of activity.
The latest addition to the insulin family is called Lente insulin. Developed in 1955 by Hallas-Moller of Denmark, this is created by adding sodium acetate to regular zinc insulin. The sodium acetate works like a buffer to maintain an acid-alkali balance. Unlike the sodium phosphate buffer employed in other insulins, the sodium acetate also has a slowing action of its own. This makes the addition of a protein like globin or protamine unnecessary.
Lente—which connotes "slowly" in Latin—has an action someplace between regular and protamine zinc insulins. Its course is about 24 hours. Although its action starts rather fast, it is not fast enough for insulin-deficient diabetics or for emergency situations induced by acidosis and coma. In such cases, if it is used the least bit, it is boosted using quick-acting regular or crystalline zinc insulin.
Today's diabetic, unlike Joe Gilchrist, has a broad range of insulins at his disposal. None of these is yet the perfect insulin. The long-lasting ones don't start in time, the quick-starting ones do not last long enough—and all of them must be injected. Moreover, while the natural insulin manufactured by the body is released only to the extent that it is demanded at any given moment, injected insulin cannot synchronize its action to the body's changing blood-sugar levels. In spite of these drawbacks, the total insulin armament is complete enough to give an answer to almost every need that may build up in diabetes.