Background
The aim of the study was to determine whether a predictive value for the diagnosis of gestational diabetes mellitus (GDM) could be established using different glucose screening test thresholds in Mexican urban pregnant women.
Material and Method
A group of 635 pregnant women (12-33 weeks of gestation) with serum glucose screening values of > or = 7.2 mmol (> or = 130 mg/dl) were evaluated with a 100-g 3-h oral glucose tolerance test (OGTT). The positive predictive values (PPVs) for serum glucose screening values of > or = 7.2 mmol to > or = 11.1 mmol (> or = 130 to > or = 200 mg/dl), age, and pregestational BMI were calculated.
Results
Of the women, 304 (47.8%) had a normal OGTT, 126 (19.8%) had impaired glucose tolerance, and 205 (32.3%) had GDM. A serum glucose screening value of > or = 9.4 mmol (> or = 170 mg/dl) had a positive predictive value (PPV) of 0.85 and the relative risk for GDM was 6.62 (95%CI: 4.40-9.97, p=0.001). Omission of the 3-h value during OGTT yielded a sensitivity of 91.2% (187/205).
Conclusions
In this group of Mexican urban pregnant women, a serum glucose screening value of > or = 9.4 mmol (> or = 170 mg/dl) had a PPV of 85%. An algorithm is proposed to reduce the number of OGTTs performed in pregnant women attending prenatal care by 36.2%.

Keywords: Mexico, Mass Screening - methods, Pregnancy, Glucose Tolerance Test, Urban Population, Diabetes, Gestational - diagnosis, Blood Glucose - analysis, Algorithms