Current trends in the diagnosis and management of gestational diabetes mellitus in the United States.

OBJECTIVE: To assess current practice patterns among members of the Society for Maternal-Fetal Medicine (SMFM) with respect to the diagnosis and management of gestational diabetes mellitus (GDM). METHODS: A 38 question survey on GDM diagnosis and management was distributed to SMFM members. RESULTS: 2330 SMFM members were surveyed with a 40% response rate. Overall, 90.6% of respondents recommend a 2-step (versus a 1-step) diagnostic test. Cutoff values for the 1-h-50 g glucose challenge test vary from 130-140 mg/dL, but the majority (83%) adopts Carpenter Coustan criteria for the 3-h-100 g oral glucose tolerance test. The majority recommend glucose testing four times a day, with 55% preferring post-prandial testing at 2 h. Glyburide is used by 57% as a first-line agent, while 4% use metformin. Long-acting insulin analogs (glargine and/or detemir) are used by 46% and 33.6% of respondents, respectively. Antenatal testing is recommended by 38.7% for diet-controlled GDM compared to 98.7% for pharmacologically controlled GDM, with 56% starting by 34 weeks gestation. Most respondents recommend delivery of diet-controlled GDM at 40 weeks and pharmacologically controlled GDM at 39 weeks. Most (69%) offer elective cesarean section for an estimated fetal weight of >4500 g. CONCLUSIONS: There is significant variation in the diagnosis and management of GDM among SMFM members.

Can a single preterm ultrasound accurately predict birth weight in gestational diabetes?

OBJECTIVE: To evaluate the accuracy of the gestation-adjusted projection method of birth weight prediction, as compared to near delivery ultrasound estimated fetal weight, in a gestational diabetic population. METHODS: A retrospective cohort was conducted including all women with gestational diabetes who had an ultrasound estimated fetal weight (EFW) between 34(0/7) and 36(6/7) weeks and an additional ultrasound EFW within 7 d of delivery at term. The gestation-adjusted projection (GAP) method was applied to the earlier sonogram, resulting in the GAP predicted birth weight. The GAP predicted weight and the term ultrasound EFW were compared to the actual birth weight. Absolute and percent birth weight errors were compared using paired t-tests. RESULTS: The mean absolute percent errors and mean absolute errors for the GAP method and term ultrasound were 7.7 ± 5.6% versus 7.1 ± 5.1% and 256 ± 184 g versus 236 ± 169 g respectively (p = 0.22 and p = 0.29). The sensitivity of predicting birth weight ≥4000 g was 22% for the GAP method and 28% for term ultrasound, with specificity reaching 97% for both the methods. CONCLUSION: The GAP method is as accurate as term ultrasound in predicting birth weight in gestational diabetes.

Glyburide transport across the human placenta.

OBJECTIVE: To estimate the magnitude of transplacental transfer of glyburide in women with gestational diabetes mellitus (GDM). METHODS: A prospective, observational study was conducted on women with GDM on glyburide therapy. On delivery admission, the glyburide dose and time of last dose were recorded. Immediately postdelivery, maternal and umbilical venous blood samples were obtained and the concentrations of glyburide were determined by high-performance liquid chromatography-mass spectrometry with a limit of detection of 0.25 ng/mL. RESULTS: Nineteen patient dyads were analyzed. The mean total daily maternal glyburide dose was 6.6±6.3 mg per day and the mean time between last dose and sampling was 13.3±6.5 hours. The mean maternal serum glyburide level at birth was 15.4±20.8 ng/mL, whereas the mean umbilical glyburide level was 7.5±8.2 ng/mL, which showed a statistical correlation (r=0.72, P<.01). There were statistically significant relationships between total maternal glyburide dose (1.25-20 mg per day) and maternal glyburide levels (0.93-70.71 ng/mL; r=0.46, P≤.01) and between total maternal glyburide dose and umbilical glyburide levels (0.95-32.41 ng/mL; r=0.43, P≤.01) However, we observed wide variability in maternal and umbilical glyburide levels at both extremes of the total glyburide dose. Seventy-nine percent of cord samples (15/19) had glyburide levels less than 10 ng/mL (the limit of detection reported in earlier studies) and 37% (7/19) were higher than the corresponding maternal samples. CONCLUSION: Transplacental transfer of glyburide is highly variable among patients, corroborating ex vivo placental perfusion studies showing a transport-mediated glyburide efflux from the fetal to the maternal circulation. In most neonates (79%), glyburide levels were below 10 ng/mL. LEVEL OF EVIDENCE: III.