Different strategies for diagnosing gestational diabetes to improve maternal and infant health

BACKGROUND: Gestational diabetes mellitus (GDM) is carbohydrate intolerance resulting in hyperglycaemia with onset or first recognition during pregnancy. If untreated, perinatal morbidity and mortality may be increased. Accurate diagnosis allows appropriate treatment. OBJECTIVES: To evaluate and compare alternative tests for diagnosis of GDM, in terms of maternal and infant health and use of health service resources. SEARCH STRATEGY: We searched the Cochrane Pregnancy and Childbirth Group’s Trials Register (31 May 2011). SELECTION CRITERIA: We included randomised trials if they evaluated tests carried out to diagnose GDM. We excluded studies that used a quasi-random model. DATA COLLECTION AND ANALYSIS: Two review authors independently assessed trials for inclusion, trial quality and extracted data. MAIN RESULTS: We identified five small trials, including 578 women. One trial compared three different methods of delivering glucose: a candy bar (39 women), a 50 g glucose polymer drink (40 women) and a 50 g glucose monomer drink (43 women). We have reported results for this trial as two separate comparisons. 75 g oral glucose tolerance test (OGTT) versus a 100 g OGTT (one trial, 248 women): women given the 75 g OGTT had a higher relative risk of being diagnosed with GDM (risk ratio (RR) 2.55, 95% confidence interval (CI) 0.96 to 6.75).This difference was borderline for statistical significance. No other measures of maternal morbidity, or outcome for the baby were reported. Candy bar versus 50 g glucose monomer drink (one trial, 82 women): women receiving the candy bar, rather than glucose monomer, reported fewer side effects (RR 0.50, 95% CI 0.26 to 0.97) and preferred the taste (RR 0.62, 95% CI 0.44 to 0.87). No outcomes were reported for the baby. 50 g glucose polymer versus 50 g glucose monomer (three trials, 259 women): mean difference (MD) in gestation at birth was -0.80 weeks (one trial, 100 women; 95% CI -1.69 to 0.09). Side effects were less common with the glucose polymer (one trial 82 women; RR 0.20 95% CI 0.07 to 0.54), with no clear difference in taste acceptability (one trial 83 women; RR 0.96; 95% CI 0.78 to 1.18). Significantly fewer women reported nausea following the 50 g glucose polymer drink compared to the 50 g glucose monomer drink (one trial 66 women; RR 0.29; 95% CI 0.11 to 0.78) and bloatedness (two trials 149 women; RR 0.22; 95% CI 0.08 to 0.60). No other measures of maternal morbidity or outcome for the baby were reported. 50 g glucose in food versus 50 g glucose drink (one trial, 30 women): women receiving glucose in their food, rather than as a drink, reported fewer side effects (RR 0.08, 95% CI 0.01 to 0.56). There was no clear difference in number of women requiring further testing (RR 0.14, 95% CI 0.01 to 2.55). No other measures of maternal morbidity or outcome for the baby were reported. AUTHORS' CONCLUSIONS: There is insufficient evidence to assess which is the best strategy for diagnosing GDM.