Abstract
Gestational diabetes mellitus (GDM) is defined as glucose intolerance with onset or first recognition during pregnancy. In the UK, approximately 2–5% of pregnancies in the UK are complicated by maternal diabetes mellitus (DM). Of these, 87.5% will have GDM. 1
GDM is associated with an increased risk of complications for the mother, including pre-eclampsia, interuterine death, stillbirth and the development of type II DM later in life. The neonate has an increased risk of macrosomia and associated birth trauma, hypoglycaemia, hyperbilirubinaemia, respiratory distress and, in the long-term, obesity and DM in childhood. However, early diagnosis and treatment of GDM can significantly reduce the risk of these complications. 2
In its recently published guidelines, 3 the National Institute of Clinical Excellence (NICE) recommended that all women with one or more risk factors for GDM including a diagnosis of GDM in the previous pregnancy, having given birth to an infant ≥4.5 kg, body mass index (BMI) ≥30 kg/m2, a first-degree relative with DM or who are of South-Asian, black Caribbean and Middle Eastern origin, should be screened using an oral glucose tolerance test (OGTT). 4 But at what cost to the patient and the National Health Service (NHS)?
It has been estimated that each OGTT takes 25 minutes of nursing time and costs the NHS £12.13, 4 with many patients considering the test inconvenient, time-consuming and unpleasant. In 2007, the University Hospital Coventry and Warwickshire (UHCW) NHS Trust performed 3543 OGTTs, approximately 12 per work day, at a cost of £42,988 and 1476 nursing hours. Of these tests, 1385 (39.1%) were performed on antenatal females (Figure 1). Of the tests performed on antenatal females, 1248 (90%) tests had a completely normal result (Figure 1). This represents a cost of £15,165 and 520 nursing hours.
Oral glucose tolerance tests performed by University Hospital Coventry and Warwickshire NHS Trust in 2007
The UHCW NHS Trust serves a population in which 16% of women have a BMI ≥30 kg/m2, 18% of pregnant women belong to ‘high-risk’ ethnic groups and the prevalence of DM is 3.7%. 5 Although it is impossible to predict what effect the recent NICE guidelines will have on the number of tests performed, it is likely that in trusts, like UHCW, which have a population with a high incidence of risk factors for GDM, the number of tests performed and the resultant costs will increase.
The proposed method of screening is expensive and non-specific with an uncertain sensitivity. Screening needs to be improved significantly before being implemented into practice.