Diabetes Information

Crystalline insulin produced less irritation at the site of injection than the original crude insulin, and it had a quick but shorter action. Hence, to control diabetes, two or three injections of crystalline insulin per day were necessary. In 1936, Hagedorn and others from Denmark reported that the action of insulin could be prolonged, if a small amount of protamine, a fish protein, was added to it. In 1937, Scott showed that an addition of zinc made this combination (protamine zinc insulin) more stable. Globin insulin and the neutral protamine Hagedorn (NPH) insulin were introduced later. These preparations of insulin could give rise to allergic reactions because they contained a foreign protein. Other preparations of insulin namely, insulin zinc suspensions (semi lente, lente and ultra lente) were available by 1952. These insulin preparations did not contain a foreign protein and were less likely to produce allergic reactions than the earlier preparations. The chemical structure of insulin was worked out by F. Sanger from Britain in 1955 for which he was awarded the Nobel prize for Chemistry in 1958. The chemical structure of insulin of many animal species has now been established and pork insulin has been shown to be more akin to human insulin than bovine insulin. Contrary to popular misconception, human insulin is not obtained from cadavers. It is prepared by a bioengineering technique.
Although relatively pure, the conventional insulin preparations still contained impurities like proinsulin (precursor of insulin) and peptides in minute quantities. Very pure insulins (monocomponent insulins) are now being prepared and marketed.
Berson and Yalow developed the technique of estimating very minute levels of insulin in the blood by using radioisotopes for which they were awarded Nobel Prize.

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