Glucose tolerance during pregnancy in Asian women

Abstract

The present study was aimed at examining differences in gestational diabetes mellitus (GDM) between two ethnic populations (immigrant Asians and indigenous White Caucasians) residing in Leicester, U.K. The study was divided into two parts: to determine the prevalence of GDM and to determine the level at which glycaemia may impose a risk to the mother and the foetus.Of a total of 12,005 pregnancies (4561 Asian and 7444 White Caucasian), over a 3-year period, 314 (6.8%) Asian and 504 (6.7%) White Caucasian were given a 75-g oral glucose tolerance test (OGTT) at 28–32 weeks for indications of ‘large for date’ pregnancies, hydramnios, glycosuria, a history of previous abortions, stillbirths, congenital abnormalities or glucose intolerance, and family history of diabetes. Abnormal glucose tolerance (AGT) was taken as a 2-h venous plasma glucose ≥ 7.8 mmol/l which reverted to normal when formally tested during the puerperium (WHO criteria, 1985). AGT was found in 1.38% Asian and 0.87% White Caucasian pregnancies (P < 0.01). This was further divided into impaired glucose tolerance (IGT) (2-h value 7.8–11.1 mmol/l) and gestational diabetes mellitus (GDM) (2-h value ≥ 11.1 mmol/l). IGT was found in 1.2% Asian and 0.84% White Caucasian pregnancies (P < 0.01), and GDM in 0.18% and 0.02% respectively (P < 0.01).Subsequently, 554 consecutive pregnancies (198 Asian and 356 White Caucasian) who had an OGTT over a 2-year period were analysed for maternal complications (toxaemia of pregnancy, Caesarian sections) and foetal complications (macrosomia, microsomia, congenital abnormalities, perinatal mortality, prematurity), according to a 2-h venous plasma glucose stratified as follows: <-4, 4.1–5, 5.1–5.5, 5.6–6.6, 6.7–7.7, 7.8–11, ≥11.1 mmol/l. There was a trend for an abnormal OGTT to occur in older and heavier women. There was a significant linear trend in the proportions of Asian maternal complications across the glycaemic bands (P < 0.05), but not so in the White Caucasian group. Foetal complications were higher in Asians in the glycaemic band > 7.8 mmol/l when compared to White Caucasians. In both ethnic groups, foetal complications appeared to be higher at the extreme ends of the glycaemic bands. However, different levels of glycaemia within the ‘normoglycaemic’ range (2-h value < 7.8 mmol/l) did not seem to adversely influence either maternal or foetal outcome in either group.In conclusion, Asian women have a significantly higher prevalence of abnormal glucose tolerance during pregnancy, with a significant linear trend in the proportion of maternal complications across glycaemic bands. Foetal complications are also higher in Asians who have a 2-h venous plasma glucose ≥ 7.8 mmol/l on OGTT. Further studies in different ethnic groups are suggested.