THE EARLY RECOGNITION OF DIABETES MELLITUS *

Progressively earlier recognition of the diabetic state is vital if progress is to be made toward the eventual control and prevention of the disease. The presence of mild diabetes mellitus may remain unrecognized in a large number of individuals for many years unless diagnostic laboratory procedures are freely employed in groups of individuals in whom experience has shown a high incidence of latent diabetes. Dependable diagnostic criteria are now available that make it possible to detect these previously unsuspected diabetic individuals. In addition, it is hoped that other means for detection of the diabetic state will be discovered that will give earlier evidence of its existence than is possible by present methods of testing. This discussion has two purposes, first, to consider the use and the criteria for the interpretation of the standard oral glucose tolerance test employed for the early detection of diabetes and second, to consider experience with the cortisone-glucose tolerance test as used for the possible prediction of future diabetes mellitus. The early recognition of diabetes mellitus depends upon the use and interpretation of proper laboratory procedures. In some cases the presence of latent diabetes will be recognized by routine performance of urinalysis and the determination of a single blood sugar level. In the mildest forms of the disease these procedures may be of little aid. In these cases the earliest recognizable abnormality may be a diminished ability to utilize a carbohydrate load as demonstrated by a glucose tolerance test. We have used the oral glucose tolerance test in our studies. For a t least 3 days preceding the test the subjects ingest a diet containing approximately 300 gm. carbohydrate per day plus maintenance calories.' Although the ingestion of smaller amounts of carbohydrate is sufficient to prevent abnormal tests in normal subjects, a standardized high-carbohydrate preparatory diet is advised to ensure the reproducibility of the test. The loading dose of glucose used is 1.75 gm./kg. of ideal body weight. Blood sugar levels are determined in venous blood by the Somogyi-Nelson technique. The criteria that we employ for the interpretation of the standard oral glucose tolerance test are illustrated in FIGURE 1.2 Carbohydrate tolerance is considered to be normal when the peak blood sugar value is less than 160 mg./ 100 ml. and the 2-hour value is less than 110 mg./100 ml. We regard the combination of an 1-hour value of 160 mg./100 ml. or above plus a 2-hour value of 120 mg./100 ml. or above as diagnostic of the existence of the diabetic state. In borderline curves the level a t 1% hours is required to be 140 mg./100 ml. or above to be diagnostic. This restriction eliminates a false diagnosis of