Abstract

The recent NICE Diabetes in Pregnancy guideline suggest the fasting and 2 h values of the 75 g oral glucose tolerance test (GTT) should be used to diagnose gestational diabetes (GDM) based on the WHO criteria. All women delivering at Chelsea and Westminster Hospital are screened at booking with a random blood glucose and at 26 weeks with a 50g glucose load (O'Sullivan's). If screen positive (≥7.8mmol/l), a full GTT is offered.

Our aim was to investigate the outcome of pregnancy in those women who only had an abnormal 1 h reading and would have been diagnosed as normal if NICE guidelines were followed. Of the 426 women diagnosed with GDM in the study period, 45 (10.6%) had an abnormal 1 h value. Complete data were retrieved for 37 women, 13 (35%) had previous GDM and 7 (19%) a family history of diabetes. The group ethnicity was 57% white, 11% Asian, 11% Black, 11% Chinese, 5% other and 5% not recorded. Home blood glucose monitoring aimed for fasting/premeal glucose levels of 3.5 mmol/l-5.5mmol/l and 1 h post meal of ≤7. 8mmol/l. 18 (49%) of the women needed treatment with metformin (8%) or insulin (41%). Macrosomia was found in 5%, polyhydramnios in 5% and pre-eclampsia in 8% of women. There was one case each of shoulder dystocia and neonatal hypoglycaemia.

The authors conclude that the inclusion of the 1 h value detects women who need treatment for hyperglycaemia to reduce maternal and fetal morbidity (as recently reported by HAPO study).