Gestational diabetes

Overview

Gestational diabetes is any degree of glucose intolerance first recognised during pregnancy. It differs from overt diabetes in pregnancy, where glucose values meet diagnostic criteria for diabetes outside pregnancy. The distinction matters because overt diabetes carries higher risks and needs specialist care from diagnosis.^[31]

The condition exists as a diagnosis because maternal glucose harms fetuses continuously. HAPO tested 25,505 women across nine countries with a 75 g tolerance test and blinded the results unless glucose reached diabetic levels.^[4] Birth weight above the 90th percentile, cord C-peptide above the 90th percentile, caesarean delivery, neonatal hypoglycaemia and pre-eclampsia all rose linearly with fasting, 1-hour and 2-hour glucose. No threshold marked a safe zone.^[4] Diagnostic cut-offs are therefore consensus lines drawn on a continuous risk curve.^[8]

GDM affects roughly one in six pregnancies in Australia under modern criteria, with higher rates among Aboriginal and Torres Strait Islander peoples, South Asian, Southeast Asian and Pacific peoples, and rates rising with obesity.^[29][14] Most women are diagnosed and managed in shared care with their GP, which makes the GP's test ordering, lifestyle counselling and follow-up the load-bearing steps.^[14]

References31ShowHide

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