The Treatment of Diabetes Mellitus.

Abstract

It is about 35 years since Banting and Best discovered insulin, and, in spite of a vast amount of research, the exact mode of action of this hormone is still unknown. The structure of the insulin molecule has been brilliantly demonstrated by Sanger and his colleagues (Ryle et al., 1955), who showed that insulin is a protein with a molecular weight of 6,000 or multiples thereof. Each molecule consists of two polypeptide chains held together by -S-Slinkages derived from the amino-acid cystine. The A chain is made up of 21 amino-acid residues and the B chain of 30. It is convenient to consider first the actions of insulin and then the effects of such actions, as the former are