New criteria for gestational diabetes in Tehran, Iran

Background: Gestational diabetes mellitus (GDM) is common problem during pregnancy. Diagnostic criteria of this problem are based on foreign population. Because of differences in racial, cultural, and nutritional characteristics, we need to determine these criteria are suitable for Iranian population.
Objective: To determine whether different diagnostic criteria of gestational diabetes mellitus (GDM) are suitable for Iranian population.
Materials and Methods: Prospective study was performed on 617 pregnant women. 1804 subjects referred for 50 g glucose challenge test (GCT) between 24th and 28^th weeks of gestation. 617 women with abnormal GCT (blood glucose ≥130 mg/dl) underwent 100-g 3-h oral glucose tolerance test (OGTT). The results were classified by three diagnostic criteria: new “Iranian” diagnostic criteria based on the results from the 100-g 3-h OGTT performed in healthy participating women; the Carpenter and Coustan (CC) criteria; and the National Diabetes Data Group (NDDG) criteria. Obstetric and neonatal outcomes were recorded.
Results: With 89% as the statistical cutoff value for the 100-g 3-h OGTT, the new diagnostic criteria were 92, 179, 153, and 121 mg/dL at 0, 60, 120, and 180 min. The K value was 0.945 for the new criteria vs. the CC criteria and 0.657 for the new criteria vs. the NDDG criteria (p<0.001). In women with GDM, the incidence rates of adverse outcomes by the new and CC criteria were similar, but higher than NDDG criteria (p<0.05).
Conclusion: Carpenter and Coustan criteria are applicable to Iranian pregnant women for diagnosis of GDM.

Keywords
Carpenter and Coustan criteria, Gestational diabetes mellitus, Iranian pregnant women, NDDG criteria, New diagnostic criteria