A study was made on correlations between carbohydrate metabolism and factors related to it, i.e., aging, obesity and disturbances of the liver. Also diagnostic criteria for diabetes mellitus were discussed.
The subjects consisted of 360 apparently healthy people who had received complete medical examinations including glucose tolerance test (GTT) at the Center for Adult Diseases, Osaka. Cases of overt diabetes diagnosed on GTT were excluded.
As a result, a mild impairment of carbohydrate metabolism which showed two-hour level of 120mg/dl or over on GTT, was found in 118 cases out of the 360 subjects. It was also found that aging, obesity and disturbances of the liver played an important role in the elevation of a twohour blood glucose level. These factors seemed to influence carbohydrate metabolism individually. For example, in cases without obesity of disturbances of the liver, the blood glucose level for one hour, as well as two hours, showed a trend of elevation as age advanced.
On the basis of the pattern of GTT curves, cases with mildly impaired carbohydrate metabolism were classified into the following four types. Over half the cases were belonged to a type showing high values at one- and two-hour blood glucose levels (designated as P type). The rest belonged to D type which showed slightly high values at two- and three-hour levels, and atypical type which showed abnormal values only at two-hour level. Besides the above-mentioned cases, there was F type which showed high fasting values with normal other values.
The cases belonging to these four types were followed up for one to two years. As a result, it was found that few cases belonging to P type and atypical type developed diabetes. On the other hand, considerably many cases of D type developed diabetes.
It was supposed to conclude that the mild impairment of carbohydrate metabolism found in the present subjects was mostly based on aging, obesity and disturbances of the liver.
It was stressed that the following points should be taken into consideration in interpreting GTT:(1) Aging should be considered as a factor which influences carbohydrate metabolism. (2) No generalized standards should be applied to cases with obesity or disturbances of the liver. A diagnosis of such cases must be established after a complete follow-up with assurance of their prognosis.
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