Proposal of the diabetic diet load test (DLT) as a new diagnostic.

The diet loading test (DLT), which measures the change in the blood sugar (BS) level after a loading diabetic diet (5 units = 400 kcal, including 50 g of carbohydrate), has been devised as a new diagnostic for diabetes. Twenty-seven and 253 patients classified as borderline type (G-B) and diabetic type (G-DM), respectively, from the results of 50 g-OGTT (GTT) were subjected to DLT to evaluate its clinical usefulness. Diagnostic criteria of DLT were established from the BS levels (mean +/- 2S.D.) in 46 normals as follows: normal type (D-N), lower than 100 mg/100 ml at baseline and than 120 mg/100 ml both 1 and 2 hr after loading; diabetic type (D-DM), higher than 120 mg/100 ml at both 1 and 2 hr; borderline type (D-B), neither of these patterns. According to these criteria, 253 patients of G-DM were divided into 249 D-DM and 4 D-B; 27 G-B were subclassified into 3 groups: 7 D-N (all of them were above 70 years old), 13 D-B and 7 D-DM (all of them were in a remission stage of diabetes). Furthermore, the results of DLT were more closely correlated with HbA1 levels, the daily profile of BS and the degree of retinopathy than those of GTT. The reproducibility of DLT was also better than that of GTT. In conclusion, DLT is a new system which makes it possible to differentiate physiological glucose intolerance in the aged and in patients in a remission state of diabetes from borderline cases diagnosed with GTT. Furthermore, it was proved that a better correlation existed between the state of BS control and the results of DLT than those of GTT. The usefulness of DLT in a population survey was also proved.