Objective: To determine the prevalence of gestational diabetes mellitus (GDM) and the patterns of glucose abnormalities during the 75-g oral glucose tolerance test (OGTT) in pregnant women; to assess the predictive value of glycated hemoglobin (HbA1c) for GDM; and to identify factors associated with GDM.
Materials and Methods: This was a cross-sectional descriptive study conducted among 267 pregnant women at 24–28 weeks of gestation.
Results: The prevalence of GDM in the study population was 28.8%. Abnormal 2-hour post-load glucose accounted for the highest proportion. The most common abnormal OGTT phenotype was combined elevation of 1-hour and 2-hour post-load glucose (35.0%). HbA1c showed fair predictive value for GDM, with an AUC of 0.728. The optimal HbA1c cut-off was 5.35%, with a sensitivity of 49.4% and specificity of 88.4%. Factors strongly associated with GDM included maternal age >35 years (OR = 3.088; 95% CI: 1.064–8.966) and a history of delivering a macrosomic infant weighing >4000 g (OR = 15.972; 95% CI: 1.890–135.008), with p <0.05.
Conclusion: OGTT was useful for detecting GDM, particularly through abnormal 2-hour post-load glucose levels. Maternal age >35 years and a history of delivering a macrosomic infant weighing >4000 g were associated with GDM. HbA1c showed fair predictive value for GDM.