Hemoglobin A1 in the diagnosis of chemical diabetes mellitus.

HbA1 was determined in 16 subjects with normal oral glucose tolerance test (OGTT), in 8 subjects with normal fasting plasma glucose (FPG) but with abnormal OGTT (chemical diabetes mellitus) and in 25 subjects with overt diabetes mellitus. The HbA1 values were 7.53 +/- 0.1%, 8.37 +/- 0.17% and 11.92 +/- 0.42% (+/- SEM), respectively. The HbA1 values of subjects with chemical diabetes mellitus were significantly higher (p less than 0.0025) than those of subjects with normal OGTT. Thus, the determination of HbA1 may prove to be useful to substantiate a significantly abnormal glucose tolerance (chemical diabetes mellitus).