DIAGNOSTIC VALUE OF FASTING PLASMA GLUCOSE (FPG) IN SCREENING OF GESTATIONAL DIABETES MELLITUS

Detecting mothers with gestational diabetes mellitus (GDM) is not only important in prevention of prenatal morbidities but also has significant effect on neonatal and maternal long term outcomes. Today, there are screening tests for GDM but they are time-consuming and expensive, therefore it seems necessary to perform testes that are uses expensive but with higher sensitivity and specificity. The aim of this study was to determine a cut - off point of fasting plasma glucose (FPG) for screening of GDM. 200 pregnant women referring to the perinatal clinic of Imam Khomeini hospital, (Sari – Iran) were studied. All cases with age ≥25 years old, history of recurrent abortion, GDM, preeclampsia, macrosomia, still birth, diabetes mellitus(DM) in first degree family or pre gestational body mass index ≥25kg/m2 were selected. Those with pre gestational diabetes mellitus were excluded. All of participants underwent a 50 g glucose challenge test (GCT) between the 24th and 28th gestational week. If 1- hour plasma glucose was more than 130 mg/dl, a 3- hour 100g oral glucose tolerance test (OGTT) was performed. The diagnosis of GDM was made by ADA 2006 recommendation (Carpenter and Coustan diagnostic criteria). Referring to the Receiver Operative Characteristic Curve, level of FPG having highest sensitivity and specificity in diagnosis of GDM was determined. From 200 participants, 65 women had positive GCT, of them 58 (response rate 89%) referred for 100g OGTT and 20(10%) were diagnosed GDM. Using ROC curve and under curve area of 0.853; the FBG level of 91.5 mg/dl, showed the highest sensitivity and specificity, 80% and 92% respectively in diagnosis of GDM. FBG ≥ 91.5 mg/dl has good sensitivity and specificity in screening of GDM. Since this is simpler and cheaper than 50g GCT, is recommended as a screening method in diagnosis of GDM.