Diabetes Mellitus: Its differentiation into insulin-sensitive and insulin-insensitive types

In previous publications it has been shown that the efficiency with which insulin acts in the body is governed by an unknown factor or condition which renders the body sensitive both to injected and pancreatic insulin. When this sensitising factor is limited the efficiency with which each unit of insulin depresses the blood-sugar is decreased, and when it is abundant the efficiency of each unit is correspondingly increased. It can easily be seen that if this sensitising factor is limited below a certain degree, then the insulin in the body will be relatively powerless and the symptoms and signs of hypoinsulinism, clinically recognisable as diabetes mellitus, will appear. This consideration led me to suggest that a type of diabetes mellitus might exist which was due, not to lack of insulin, but rather to lack of this sensitising factor. An investigation of cases of diabetic patients from this point of view was therefore commenced. At first sight the simplest method of testing this hypothesis would appear to be by comparing in different diabetic subjects the rate and extent of fall of the bloodsugar after a standard dose of insulin. Such comparison of insulin depression curves from diabetic patients is, however, impossible. Insulin depression curves are only comparable when obtained from one and the same subject and, even then, only if the initial blood sugar values of the different curves are within a few mg. per 100 c.cm of the same level. A new test was therefore sought and found in the application of an observation previously made on animals. If glucose and insulin are given simultaneously to a normal animal, then the extent to which the injected insulin suppresses the hyperglycaemia can be gauged by comparing the blood-sugar curve resulting from glucose alone with the curve resulting from glucose plus insulin.