Evaluation of new criteria for diagnosis of diabetes mellitus based on follow-up study of borderline diabetes.

In order to evaluate the validity of recently proposed criteria for diagnosis of diabetes mellitus, a retrospective study was performed in 315 patients with borderline diabetes, who were selected from approximately 4,000 outpatients under treatment for more than three years. They were divided into two groups, BI and BII, according to the 2-hr blood glucose level in the 50 g glucose tolerance test (GTT): BI between 100 and 135 mg/100 ml and BII between 135 and 195 mg/100 ml. In group BI, glucose tolerance was deteriorated in 38 of 75 patients (51%) and converted to diabetes mellitus in 21 patients (28%). In group BII, 78 among 232 patients (34%) developed diabetes mellitus. Furthermore, in 85% of the 99 cases of the conversion to diabetes mellitus from borderline diabetes, it occurred within 5 years. Diabetic retinopathy was observed in 25 of 72 patients (35%) in group BI and in 60 of 212 patients (28%) in group BII. More than two thirds of the patients with diabetic retinopathy observed in the borderline diabetes developed their retinopathy within 5 years. Normal insulin response during GTT was proved only in 21% and 17% among groups BI and BII, respectively. These results indicate that the patients with borderline diabetes BI as well as BII, are closely related with diabetes mellitus, and that the patients with impaired glucose tolerance should be treated with diet restriction as in diabetes mellitus.