What is gestational diabetes?
Throughout pregnancy, the placenta acts as an
endocrine organ producing numerous hormones
including oestrogen, cortisol and human placental
lactogen (HPL). These hormones inhibit the
function of insulin, thereby causing a rise in
the mother’s blood glucose levels. The resultant
increase in blood glucose commonly occurs in the
second (13–28 weeks) and third (29–40 weeks)
trimesters, when placental hormones are produced
in excess. With increasing insulin resistance, the
pancreas is stimulated to produce increasing levels
of insulin. When the pancreas cannot meet the
increased insulin demand, this results in GDM.
In the HAPO study (HAPO Study Cooperative
Research Group, 2002), a global population of
approximately 25000 non-diabetic women were
studied. A continuous relationship between
glycaemia and adverse pregnancy outcome was
demonstrated. The adverse pregnancy outcomes
reported included primary caesarean section and
high birth weight. A greater association was found
between maternal glucose levels at 24–32 weeks’