Oral glucose tolerance testing at gestational weeks < or =16 could predict or exclude subsequent gestational diabetes mellitus during the current pregnancy in high risk group.
BACKGROUND
An oral glucose tolerance test with a result that is negative but close to the diagnostic cut-off in early pregnancy was hypothesized to serve as a predictor of subsequent gestational diabetes in a high risk group. The aim of the study was to determine those cut-off values of OGTT at gestational weeks < or =16, which can predict or exclude subsequent onset of GDM in a high risk group.


METHODS
Pregnant women at high risk of gestational diabetes (n = 163) underwent a 2-h, 75-g oral glucose tolerance test at gestational weeks < or =16 were analyzed in this study. In the event of a negative result, subsequent oral glucose tolerance tests were performed at gestational weeks 24-28 and 32-34. The sensitivity, the specificity, the positive and negative predictive values and the Odds ratio of the best cut-off values of fasting and postload glucose levels were calculated.


RESULTS
The best cut-off values to exclude subsequent GDM for fasting and postload glucose were 5.0 and 6.2 mmol/l, respectively. In combination, the best cut-off values were 5.3 mmol/l for fasting and 6.8 mmol/l for postload glucose, with negative predictive values of 0.97 and 0.71 and sensitivities of 96.9 and 86.3 at gestational weeks 24-28 and 32-34, respectively. Combination of these cut-off values with obesity proved to be very predictive for gestational diabetes by gestational weeks 32-34, with an Odds ratio of 6.0 [95% confidence interval: 1.7-21.0].


CONCLUSIONS
With regard to the very high negative predictive value of the method, pregnant women with glucose levels of < or =5.3 mmol/l at fasting and of < or = 6.8 mmol/l at postload in gestational weeks < or =16 should undergo subsequent oral glucose tolerance testing merely at gestational weeks 32-34. Approximately a quarter (24.5%) of the pregnant women at risk of gestational diabetes satisfied these criteria.
Department of Obstetrics and Gynaecology, University of Szeged, Albert Szent-Györgyi Medical and Pharmaceutical Center, Hungary. bito@obgyn.szote.u-szeged.hu
Tamás
T
Bitó
Tibor
T
Nyári
László
L
Kovács
Attila
A
Pál
D000328:Adult; D017677:Age Distribution; D001786:Blood Glucose / Q000032:analysis; D016001:Confidence Intervals; D016640:Diabetes, Gestational / Q000175:diagnosis* / Q000453:epidemiology*; D005260:Female; D005951:Glucose Tolerance Test; D006801:Humans; D015994:Incidence; D008403:Mass Screening; D016017:Odds Ratio; D011237:Predictive Value of Tests; D011247:Pregnancy; D011256:Pregnancy Outcome; D011262:Pregnancy Trimester, Second; D018566:Pregnancy, High-Risk; D011295:Prenatal Care; D011336:Probability; D011446:Prospective Studies; D018570:Risk Assessment
D001786:Blood Glucose