The threshold criteria for the 75g oral glucose tolerance test in pregnancy and short-term adverse pregnancy outcomes

Abstract

The significant threshold values for the 75g oGTT during pregnancy have yet to be conclusively determined. The study aimsto identify the risk significance of a borderline oGTT result. Women undergoing a 75g OGTT during the third trimester ofpregnancy were classified into two groups - borderline tolerance (2-h post-load glucose 8.0-8.5 mmol/l: n=75), and GDM(≥8.6 mmol/l: n=236). Outcome indicators of these two groups of women were compared to the parameters of the womenwith a presumed normal carbohydrate metabolism (n = 12185). GDM women showed themselves to be at a significantlyincreased risk of developing hypertensive disorders during pregnancy and to require obstetric intervention in the form ofinduction of labour and caesarean section. Their infants were more likely to be macrosomic or preterm and having a lowApgar score at birth. Shoulder dystocia was similarly more likely in infants born to GDM mothers. Women with borderlineglucose tolerance did not in any way show any statistically significant increased predisposition to these complications. Itwould appear the significant threshold for the 75g oGTT during pregnancy should be of the order proposed by the AmericanDiabetes Association criteria where the 2-hour post-load glucose value is ≥ 8.6 mmol/l.