More than a third of women who suffer from diabetes during pregnancy develop type 2 diabetes within five years and those most at risk can be predicted from their blood glucose levels at diagnosis, according to a study published in the June issue of the Postgraduate Medical Journal.
While assessing plasma blood glucose levels using the HbA1c test is not a very sensitive method for diagnosing gestational diabetes, those women with higher HbA1c levels when this type of diabetes is diagnosed are much more at risk of developing type 2 diabetes later. HbA1c is a measure of the amount of blood glucose attached to the haemoglobin of red blood cells.
Almost half of the South Asian and a quarter of the Caucasian women who experienced gestational diabetes developed type 2 diabetes within five years. But the risk of future diabetes was only 10 per cent in Caucasian women with HbA1c <6.1 and South Asian women with HbA1c <6.15.
The researchers studied 189 women in Leicestershire who were diagnosed with gestational diabetes between 1995 and 2001, and 73 women (36 South Asian and 37 Caucasian) agreed to be followed up.
Four to five years after gestational diabetes only a third of South Asian and half of Caucasian women had normal glucose tolerance. The authors said the findings highlight the need for proactive screening for diabetes in women with previous gestation diabetes mellitus. This is an impaired glucose tolerance first recognised during pregnancy, it affects around 5% of pregnant women.
The importance of early identification of diabetes is set out in standard 2 of the National Screening Framework for diabetes.