Glycosylated hemoglobin: a sensitive indicator of gestational diabetes.

Previous studies suggested that the assessment of hemoglobin A1 (HbA1) concentration was a poor indicator of diabetes in pregnancy. However, HbA1 was measured by ion exchange chromatography, which is subject to spurious alterations. To reevaluate the use of glycosylated hemoglobin concentration (GlyHb) as an indicator of gestational diabetes, 64 women at 10 to 15 weeks' gestation were studied by measuring GlyHb by a specific affinity chromatography assay, and blood glucose concentration was determined one hour post a 50-g oral glucose load. Gestational diabetes developed in 15 women in whom GlyHb (7.4 +/- 0.2%) was greater than in normal pregnant women (5.7 +/- 0.1%, P less than .001). If a GlyHb of 6.3% were chosen as the threshold for diagnostic evaluation for diabetes, only 6.7% of the gestational diabetics would have missed diagnosis. Of normal women, 14.2% would have been subjected to glucose tolerance test. GlyHb elevation was associated with the birth of infants large for gestational age. The assessment of GlyHb by affinity chromatography between 10 and 15 weeks' gestation may be a sensitive predictor of patients who will develop gestational diabetes.