Risk factors for gestational impaired glucose tolerance in the Maltese population: a cross-sectional study

Screening criteria for impaired carbohydrate metabolism problems during pregnancy include the use of specified risk factors, which are generally considered to be inadequate. The value of these risk factors in a population characterised by a high prevalence of abnormal carbohydrate metabolism is investigated. The study identified biological characteristics such as a maternal age >35 years, previous early pregnancy loss, a maternal family history of DM/IGT, pre-prandial glucosuria and an operative delivery with resuscitation as significant risk factors for the development of G-IGT. There appeared to be no statistical association with a history of multiparity, previous perinatal loss, congenital anomalies or macrosomia and a parental and grandparent family history of DM/IGT. There appeared to be a statistical difference in fasting blood glucose values, but no difference in glycosated haemoglobin. The risk factors for the development of G-IGT are shown to have a high specificity and negative predictive value, but overall moderate to low sensitivity and positive predictive values when used in isolation. The prevalence of the various identified risk factors was very high, a feature which would require at least a third of the population to be screened with an oral glucose tolerance test. These features suggest that the historical and clinical risk criteria are not ideal screening tools to identify G-IGT and a routine early third-trimester oral glucose tolerance test remains the ideal screening tool to identify these cases.