The risk factors for GDM and the value of the screening test

The risk factors of gestational diabetes mellitus (GDM) associated have been largely derived from populations of European extraction, and there are few studies examining this issue in Iran. According the ADA recommendation the cut- off point of screening test with 50 gr glucose to 130 mg/dL has been decreased, So this study was conducted to determine of the risk factors of GDM in Iranian pregnant women of Shahrood city and comparison the value of screening test with two different cut off points (130 and 140 mg/dL). In a general screening for 1310 pregnant women referring to the Fatemiyeh Hospital, 12 risk factors were considered at the first screening. On the other in order to determine the value of the screening test without taking into account the results of the initial screening test, the OGTT was done with 100 gr oral glucose for the first 459 pregnant women. All measurements of serum glucose were performed by the glucose oxidase method at the Fatemiyeh Hospital Laboratory. According to the Logistic model, the most important of risk factors included: Glucosuria, previous macrosomia, obesity, family history of diabetes, age ≥ 30 yr and previous unknown neonate’s death. Glucosuria had the highest odds ratio (OR=41.7,CI=15.7-110.3,P<0/001) and positive predictive value (P.P.V) (63%) and the lowest odds ratio was related to age ≥ 30yr (OR=3, CI=1.8-5, P<0/001). A sensitivity of 97%, specificity of 81%, P.P.V of 27% and a negative predictive value N.P.V of 99.7% of GCT 50gr were determined with a 130 mg/dL cut off point and a sensitivity of 85%, specificity of 88%, a P.P.V of 35% and N.P.V of 99% with a 140 mg/dL cut off point. Recognized risk factors of GDM were valid for our population. Use of 130 mg/dL as a cut off point in the screening test demonstrated a higher N.P.V and sensitivity, indicating this to be a better cut off point for diagnosis of women with GDM.