The value of maternal glycosylated haemoglobin (HBA1c) and
fructosamine in the prediction of
gestational diabetes is debated. One hundred high risk patients were grouped as normal,
impaired glucose tolerance (IGT) and
gestational diabetes mellitus, according to the WHO criteria, after 2 hours, 75 g oral
glucose tolerance test (OGTT). Maternal HBA1c and
fructosamine were measured at different gestational ages and at the start of labour. The aim of the study was to determine the most sensitive predictor of abnormal
glucose tolerance. Maternal
fructosamine was higher in gestational diabetics than in the other two groups, but the difference was not of statistical significance. The values for normal and IGT groups overlapped markedly. The
fructosamine test sensitivity was 12.2%, specificity was 94.7% and predictability was 75%. Glycosylated haemoglobin was significantly higher in IGT and
gestational diabetes mellitus (GDM) groups than in the normal group after 36 weeks of gestation. At 32 weeks or less the difference was not of statistical significance. As with
fructosamine, there was a wide range of value that overlapped markedly, particularly between the normal and IGT patients. The HBA1c test sensitivity was 19.1%, specificity was 95% and predictability was 81.1%. This suggests that both HBA1c and
fructosamine have very low sensitivity as predictors of gestational
glucose intolerance.