Glycosylated haemoglobins in women with low risk for diabetes in pregnancy.

Abstract

Glycosylated haemoglobin levels (HbA1) were determined in 489 normal pregnant Singaporean women, attending a diabetic screening programme using a 50g glucose challenge test. All subjects had no risk factors for diabetes mellitus nor a history of previous gestational diabetes. They were selected when the 1h 50g glucose challenge (GCT) is < 6.66 mmol/l or a 2h post-glucose level of < 7.77 mmol/l (a 75g OGTT is repeated within a week of an abnormal GCT). Another 18 subjects with normal OGTT but did not have a 50g glucose challenge done were also included in the study. Mean and normal range (2 SD) of HbA1 levels in all subjects were 4.64% and 3.66-5.62%, respectively. Mean HbA1 levels also varied with gestation and ethnic group. The HbA1 appeared to be low at early gestation with nadir at 21-24 weeks and thereafter returned to initial levels at term. In Chinese, mean HbA1 levels, random plasma glucose and 1h glucose challenge were significantly higher than those of the Malays but not the Indians. In referring to these levels, the variation within gestation and ethnic group must also be considered.