THE DIAGNOSIS OF PATHOLOGICAL HYPERGLYCEMIA IN GESTATIONAL DIABETES IN A HIGH-RISK OBSTETRIC POPULATION

In order to define a level of 'pathological hyperglycaemia', i.e. gluc ose intolerance that predicts perinatal morbidity among the obstetric population, 100 g glucose tolerance tests (GTTs) were performed in 660 patients attending for antenatal care at the University Hospital in J eddah. The results were analysed in two ways: (1)patients were stratif ied according to the number of abnormal glucose values on the GTTs and (2) patients were placed into one of three groups according to the 10 0 g GTT diagnostic criteria, i.e. normal (non-GDM), abnormal with fast ing blood glucose (FBG) greater than or equal to 5.8 mmol l(-1) (GDM), and abnormal with FBC <5.8 mmol l(-1) (gestational induced hyperglyca emia, GIH). Although there was a stepwise association between fetal/ma ternal morbidity with increasing number of abnormal glucose values, no level of glucose intolerance could be defined as a threshold level fo r normal response. However, when stratified by FBG, GDM patients were significantly heavier (78.5 kg +/- SD 14.9), had a higher incidence of both macrosomia (27.5%) and operative delivery (25.3 %) than the othe r two groups (14.7%, 14.3%, and 15.4%, 12.8% in the non-GDM and GIH, r espectively). It is suggested that among patients with abnormal GTT re sults a FBG greater than or equal to 5.8 mmol l(-1) identifies a thres hold for true 'pathological hyperglycaemia'.