WHICH CUTOFF LEVEL SHOULD BE USED IN SCREENING FOR GLUCOSE-INTOLERANCE IN PREGNANCY

OBJECTIVE: Our purpose was to examine the validity of 140 mg/dL cutoff value in oral glucose challenge test screening for gestational diabet es mellitus when including in the group to be identified women fulfill ing more inclusive Carpenter and Coustan criteria for 100-g oral gluco se tolerance testing interpretation and gravid women with borderline g lucose intolerance. STUDY DESIGN: We reanalyzed data of a multicenter study performed on 704 pregnant women screened at the twenty-fourth to twenty-eighth week with a 50-9 oral glucose challenge test followed b y a universal 100-g oral glucose tolerance test. We used receiver-oper ator characteristic curve analysis, assembling positive and negative g roups according to the different criteria adopted in oral glucose tole rance test interpretation (National Diabetes Data Group or Carpenter-C oustan) and in assignment of women with borderline glucose intolerance . Besides the statistical cutoff value, defined by the Youden index (S ensitivity + Specificity - 1), we also selected a ''high-sensitivity'' cutoff value, identified by the maximal sensitivity associated with > 70% specificity RESULTS: With use of National Diabetes Data Group crit eria, the statistical and high-sensitivity cutoff values were set at 1 42 mg/dL when the positive group included only women with positive ora l glucose tolerance test results and at 140 mg/dL when it also include d subjects with borderline glucose intolerance. With use of Carpenter- Coustan criteria, the statistical cutoff value was set at 141 mg/dL wh en the positive group included only women with positive oral glucose t olerance test results and at 140 mg/dL when it also included subjects with borderline glucose intolerance; the high-sensitivity cutoff value was set at 140 mg/dL when the positive group included only women with positive oral glucose tolerance test results and at 136 mg/dL when it also included subjects with borderline glucose intolerance. CONCLUSIO NS: We suggest maintaining the 140 mg/dL oral glucose challenge test t hreshold if the diagnostic target is to recognize only women with posi tive results of the oral glucose tolerance test. To prevent perinatal risks in pregnancies complicated by borderline glucose intolerance, wi th Carpenter-Coustan criteria a lower cutoff value (136 mgidL) could b e hypothesized to improve test sensitivity, allowing more extensive di agnosis of ''borderline'' subjects; however, the higher economic costs resulting from the increased false-positive rate and the limited impr ovement obtainable in sensitivity currently do not justify its general ized use.