Screening and Diagnosis of Gestational Diabetes Mellitus, Where Do We Stand

Gestational Diabetes Mellitus (GDM) is defined as any glucose intolerance with the onset or first recognition during pregnancy. This definition helps for diagnosis of unrecognized pre-existing Diabetes also. Hyperglycemia in pregnancy is associated with adverse maternal and prenatal outcome. It is important to screen, diagnose and treat Hyperglycemia in pregnancy to prevent an adverse outcome. There is no international consensus regarding timing of screening method and the optimal cut-off points for diagnosis and intervention of GDM. DIPSI recommends non-fasting Oral Glucose Tolerance Test (OGTT) with 75g of glucose with a cut-off of ≥ 140 mg/dl after 2-hours, whereas WHO (1999) recommends a fasting OGTT after 75g glucose with a cut-off plasma glucose of ≥ 140 mg/dl after 2-hour. The recommendations by ADA/IADPSG for screening women at risk of diabetes is as follows, for first and subsequent trimester at 24-28 weeks a criteria of diagnosis of GDM is made by 75 g OGTT and fasting 5.1mmol/l, 1 hour 10.0mmol/l, 2 hour 8.5mmol/l by universal glucose tolerance testing. Critics of these criteria state that it causes over diagnosis of GDM and unnecessary interventions, the controversy however continues. The ACOG still prefer a 2 step procedure, GCT with 50g glucose non-fasting if value > 7.8mmol/l followed by 3-hour OGTT for confirmation of diagnosis. In conclusion based on Hyperglycemia and Adverse Pregnancy Outcome (HAPO) study as mild degree of dysglycemia are associated with adverse outcome and high prevalence of Type II DM to have international consensus It recommends IADPSG criteria, though controversy exists. The IADPSG criteria is the only outcome based criteria, it has the ability to diagnose and treat GDM earlier, thereby reducing the fetal and maternal complications associated with GDM. This one step method has an advantage of simplicity in execution, more patient friendly, accurate in diagnosis and close to international consensus. Keeping in the mind the diversity and variability of Indian population, judging international criteria may not be conclusive, thus further comparative studies are required on different diagnostic criteria in relation to adverse pregnancy outcomes.