Clinical implications of the 100-g oral glucose tolerance test in the third trimester

Timing of gestational diabetes diagnosis and progression to type 2 Diabetes: A comparative analysis

AIM

To evaluate and compare the risk of progressing to type 2 diabetes (T2DM) based on the timing of gestational diabetes (GDM) diagnosis during pregnancy.

METHODS

Retrospective analysis of pregnant individuals with gestational diabetes and post-pregnancy follow up. Data sourced from Meuhedet HMO's computerized laboratory system, cross-tabulated with the Israeli National Diabetes Registry. The cohort was divided into normoglycemic, early GDM (diagnosed by fasting plasma glucose 92-125 mg/dL (5.1-6.9 mM) at < 15 weeks), 2nd trimester GDM (diagnosed at 24-28 weeks), and late GDM (diagnosed after 29 weeks). Statistics included univariate analysis followed by survival analysis. Risk was further analyzed for individuals by obesity status.

RESULTS

75,459 entered the analysis: 90 % normoglycemic, 7.9 % early GDM, 1.4 % 2nd trimester GDM, and 0.7 % late GDM. Median post-pregnancy follow-up time was 4.3 (IQR 3.3-5.1). 2nd trimester GDM showed the highest T2DM risk annually after pregnancy. Cox regression analysis, adjusted for confounders, revealed a significantly higher T2DM risk for 2nd-trimester GDM compared to early and late GDM. Late GDM did not confer additional significant T2DM risk. Stratification by obesity status highlighted that early GDM increased the risk of T2DM only in individuals without obesity.

CONCLUSIONS

GDM diagnosis timing significantly impacts T2DM risk. 2nd trimester GDM carries the highest T2DM risk.

The impact on pregnancy outcomes of late-onset gestational diabetes mellitus diagnosed during the third trimester: A systematic review and meta-analysis

BACKGROUND

Evidence is inconsistent regarding the impact of late gestational diabetes mellitus (GDM) on perinatal outcomes.

OBJECTIVES

To evaluate associations of GDM diagnosed in the third trimester (late GDM) with adverse obstetric and neonatal outcomes.

SEARCH STRATEGY

We searched Embase, Medline, and Web of Science from January 1, 1990 to June 16, 2022, for observational studies.

SELECTION CRITERIA

Late GDM was defined as a de novo diagnosis, i.e. after a negative screening for diabetes in the second trimester, and at later than 28 weeks of pregnancy.

DATA COLLECTION AND ANALYSIS

Each abstract and full-text article was independently reviewed by the same two authors. Quality was assessed with the use of the Newcastle-Ottawa Scale. Summary odds ratios (ORs) and 95% confidence intervals (CIs) were calculated using a random effects model.

MAIN RESULTS

Twelve studies were identified as meeting the inclusion criteria, including 3103 patients (571 with late GDM and 3103 controls). Incidences of shoulder dystocia (OR 1.57, 95% CI 1.02-2.42, P = 0.040), 5-minute Apgar score <7 (OR 1.80, 95% CI 1.14-2.86, P = 0.024), cesarean delivery (OR 1.98, 95% CI 1.51-2.60, P < 0.001), and emergent cesarean delivery (OR 1.57, 95% CI 1.02-2.40, P = 0.040) were significantly higher among women with late GDM than among the controls. The groups showed similarity in the rates of fetal macrosomia, large-for-gestational-age fetuses, neonatal hypoglycemia, and hypertensive disorders of pregnancy.

CONCLUSIONS

This meta-analysis showed associations of late GDM with increased adverse perinatal outcomes. Prospective studies should evaluate the impact on perinatal outcomes of repeated third-trimester screening for late GDM.

Obstetrical Outcome following Diagnosis of Gestational Diabetes in the Third Trimester (>29 Weeks) versus Second Trimester (24-28 Weeks): A Retrospective Comparative Study

OBJECTIVE

This study aimed to compare obstetrical outcomes between women diagnosed with gestational diabetes mellitus (GDM) in the third trimester after testing negative for GDM in two-step screening in the second trimester and women diagnosed in the second trimester.

STUDY DESIGN

This retrospective study compared obstetrical outcomes between 375 women diagnosed with GDM in the second trimester and 125 diagnosed in the third trimester.

RESULTS

Among women diagnosed with GDM in the third versus second trimester, the incidences were higher of morbid obesity (body mass index ≥35 kg/m2), macrosomia, and cesarean section (CS) due to suspected macrosomia: 23.2 versus 9.8%, p < 0.001; 44.0 versus 10.1%, p < 0.001; and 24.8 versus 6.3%, p < 0.001, respectively. For those diagnosed in the third versus second trimester, the incidences were lower of hypertensive disorders of pregnancy and intrauterine growth restriction, and a lower proportion of women needed pharmacological therapy for glucose control: 2.4 versus 9.0%, p = 0.016; 0.8 versus 8.2%, p < 0.001; and 12.0 versus 29.7%, p < 0.001, respectively. Multivariate analysis supported a correlation between third-trimester-diagnosed GDM and macrosomia, and between second-trimester-diagnosed GDM and hypertensive disorders of pregnancy.

CONCLUSION

Among women diagnosed with GDM in the third compared with the second trimester, the incidence of morbid obesity was higher; accordingly, the risks were higher for large for gestational age infants and delivery by CS, and lower for hypertensive disorders. Guidelines regarding repeat oral glucose tolerance testing in the third trimester should be considered following prospective studies.

KEY POINTS

· Third-trimester GDM was 29.9% among women with normal second-trimester screening.. · Morbid obesity and macrosomia were more frequent in third- versus second-trimester GDM.. · Incidence of preeclampsia was lower in third- versus second-trimester-diagnosed GDM..

Third trimester re-screening for gestational diabetes in morbidly obese women despite earlier negative test can reveal risks for obstetrical complications

AIM

We investigated associations of maternal obesity with late gestational diabetes mellitus (GDM) diagnosis (>34 weeks) in women with previous normal glucose screening, and associations of late GDM with obstetrical outcomes.

METHODS

This retrospective cohort study assessed obstetrical and neonatal outcomes of 238 women with normal (24-28 week) glucose screening results, who underwent late repeat oral glucose tolerance tests (OGTT) (>34 weeks) due to a suspected LGA fetus (54.6%) or polyhydramnios (45.4%). A sub-analysis was performed of outcomes of women with late versus mid-trimester GDM.

RESULTS

The GDM rate in repeat OGTT screening was 22.2% for the total sample, and 33% among women with morbid obesity. Among women with late GDM versus without late GDM, rates were higher for macrosomia, large-for-gestational-age fetus induction of labor, neonatal hypoglycemia, jaundice, and the need for phototherapy. Among women with late GDM, a higher pregestational BMI was associated with adverse maternal and perinatal outcomes. Higher risks for macrosomia and CS due to macrosomia were demonstrated in women with late vs. mid-trimester GDM.

CONCLUSION

Late screening in pregnancy may reveal GDM among women with previous normal glucose screening, particularly among those with late third trimester BMI ≥ 35 kg/m² , GDM in a previous pregnancy or fasting glucose >95 mg/dl. Women diagnosed with GDM at >34 weeks following normal glucose screening at 24-28 weeks are at higher risk for adverse perinatal outcomes. For women with morbid obesity, or suspected macrosomia or polyhydramnios in the late third trimester, and normal glucose screening in the second trimester, retesting should be considered.