Background & Objectives: Gestational Diabetes Mellitus (GDM) is defined as carbohydrate intolerance of variable severity with onset or first recognition during the pregnancy. Diagnosis of this disorder can prevent complications in mother and her fetus during pregnancy. This study was an attempt to determine GDM prevalence in pregnant women referring to Ardabil health centers.

 Methods: In this cross-sectional study 601 pregnant women with 24-28 weeks of gestational age were screened by glucose challenge test (GCT) using 50 gr of oral glucose. GCT was considered positive if the serum level of glucose was larger than or equal to 140 mg/dl. Oral Glucose Tolerance Test (OGTT) was done on GCT⁺ subjects with 100 gr oral glucose. The diagnostic criteria were these of National Diabetes Data Group.

 Also a questionnaire was used to record history, age, height, blood pressure, weight before pregnancy and other characteristics. The data were analyzed using SPSS software.

 Results: From 601 pregnant women, 64 cases (10.6%) were GCT⁺. OGTT indicated that from these 64 cases, 8 cases had GDM (GCT ⁺, OGTT⁺). GDM prevalence was estimated 1.3%. There was a statistically significant relationship between BMI, mean age and mean diastolic blood pressure on the one hand and GCT and GDM positivity on the other (p<0.05). There was a significant relationship between increasing of BMI and the prevalence of GDM positivity GCT (p<0.05), but the relation was not significant between increasing of systolic blood pressure and gravidity with prevalence of GDM and positive GCT.

 Conclusion: It seems that the prevalence of GDM in Ardabil is low and general screening is not necessary for all pregnant women. The prevalence of GDM showed an increase with the age of pregnant women, BMI and obesity.