Glycated hemoglobin of fractionated erythrocytes, glycated albumin, and plasma fructosamine during pregnancy.

OBJECTIVE: To evaluate glucose metabolism during pregnancy, we measured plasma fructosamine, glycated albumin, and the stable glycated hemoglobin of the light and dense erythrocytes. STUDY
DESIGN: The abnormal glucose tolerance group comprised patients with gestational diabetes and those with one abnormal value on a 75 gm oral glucose tolerance test. Erythrocyte fractionation was performed by capillary centrifugation.
RESULTS: In normal pregnancy glycated hemoglobin of the light erythrocytes was reduced in the second and third trimesters (3.42% +/- 0.62% [mean +/- SD] [n = 306] in the first trimester, 2.15% +/- 0.48% [n = 353] in the second, and 2.06% +/- 0.58% [n = 300] in the third), and dense erythrocytes were higher in the third trimester (first 4.59% +/- 0.46%, second 4.70% +/- 0.49%, third 5.29% +/- 0.73%). Glycated albumin and fructosamine followed a pattern similar to the light erythrocytes. The group with abnormal glucose tolerance had significantly higher levels of glycated hemoglobin of the light erythrocytes in the first and third trimesters and glycated hemoglobin of the dense erythrocytes and glycated albumin in all trimesters.
CONCLUSION: The biphasic change in nonfractionated glycated hemoglobin is the sum of the lower glycated hemoglobin of the light erythrocytes and the higher glycated hemoglobin of the dense erythrocytes in late pregnancy. The stable glycated hemoglobin of fractionated erythrocytes and the glycated albumin accurately reflect maternal glucose metabolism during pregnancy.