Validity of Fasting Blood Glucose Test in Screening for the Pre-Diabetes State Among Pregnant Females

Gestational diabetes mellitus (GDM) is defined as carbohydrate intolerance of varying degrees of severity with onset or first recognition during pregnancy (Metzer & Coustan, 1998). Glucose tolerance deteriorates in human pregnancy, but about 97% to 98% of all pregnant women retain a normal glucose tolerance and only 2% to 3% develops GDM (Kuhl, 1991). However, failure to diagnose and treat GDM will result in increased morbidity in some pregnancies, while an aggressive approach to diagnosis and treatment may result in unnecessary intervention in others (Kjos & Buchanan, 1999). The prevalence of GDM ranges from 1% to 14% of all pregnancies, depending on the population studied and the diagnostic tests and criteria employed (World Health Organization [WHO], 1985). In a recent study by Al-Rowaily and Abolfotouh in Riyadh, Saudi Arabia, the prevalence of GDM was 12.5% and 3.8% by the WHO and American Diabetes Association criteria respectively (Al-Rowaily & Abolfotouh, 2010). The appropriateness of these different diagnostic criteria has been debated (Gabir et al., 2000); nevertheless women meeting the definition for GDM by either set of criteria are at greater risk of complications than women without the diagnosis. The 75-g glucose load has been the international standard for the diagnosis of diabetes in nonpregnant adults for several decades. This oral glucose tolerance test (OGTT) identifies pregnant women who are at risk of pre-eclampsia and whose babies are at risk of macrosomia and perinatal mortality (Schmidt et al., 2001). Although the American Diabetes Association (ADA) still recommends a 3-h 100-g OGTT for the diagnosis of GDM, it has recently included in its recommendations the use of a 2-h 75-g OGTT (American Diabetes Association [ADA], 2000; Metzger & Coustan, 1998). A recent WHO panel, although in general maintaining previous diagnostic recommendations, now characterizes GDM as the joint category of diabetes and impaired glucose tolerance (fasting glucose ≥ 7.0 mmol/L or 2-h glucose ≥ 7.8mmol/L (WHO, 1999). At present, screening for gestational diabetes appears to be hampered by the lack of a clear definition, agreed diagnostic criteria and evidence to show that intervention and treatment for this condition leads to improved outcomes for the mother and fetus. Although fasting plasma glucose and Glucose Challenge Test (GCT) have the highest reported sensitivities