Fasting glucose at GDM diagnosis may predict postpartum glucose abnormalities

Fasting glucose at GDM diagnosis may predict postpartum glucose abnormalities | Image Credit: © KaterynaNovikova - © KaterynaNovikova - stock.adobe.com.

Abnormal fasting glucose levels at gestational diabetes mellitus (GDM) diagnosis may be a predictor of postpartum glucose abnormalities in pregnant women, according to a recent study published in Archives of Gynecology and Obstetrics.¹

Approximately 15% of normal pregnancies are impacted by GDM, which has been linked to adverse maternal and neonatal outcomes. Guidelines recommend glucose testing at 6 to 12 weeks postpartum in women with a history of GDM to prevent or delay diabetes onset.²

Impaired glucose tolerance or overt diabetes after delivery has been estimated in up to 25% of GDM patients.¹ However, according to investigators, “the association between fasting glucose levels at diagnosis of GDM and postpartum (within 6 weeks) glucose abnormalities remains unclear.”

A retrospective study was conducted to evaluate this association. Participants included women diagnosed with GDM between January 2022 and December 2022 at the study hospital receiving at least 6 weeks of follow-up after delivery. Those with a history of diabetes were excluded from the analysis.

GDM was determined by fasting circulating blood glucose levels over 5.1 mmol/L or levels over 10.0 mmol/L at 1 hour of 75 g- oral glucose tolerance test (OGTT) or over 8.5 mmol/L at 2 hours of 75 g-OGTT at 24 to 28 weeks’ gestation. Participants also underwent a fasting plasma glucose test at 6 weeks postpartum.

At the 6-week measurement, fasting plasma glucose levels under 5.6 mmol/L were considered normal, 5.6 to 6.9 mmol/L impaired, and levels over 7.0 mmol/L diabetes mellitus. Only 2 women in the sample had postpartum levels over 7.0 mmol/L and were excluded from the final analysis.

The hospital’s database was assessed for relevant data. This included maternal age at diagnosis, blood glucose levels at diagnosis, postpartum fasting plasma glucose levels, gestational age at diagnosis and delivery, maternal body mass index (BMI) at pregnancy, birthweight, 1- and 5-minute Apgar scores, pregnancy complications, weight gain, and treatment options.

Preeclampsia was defined as maternal systolic blood pressure over 140 mmHg or diastolic blood pressure over 90 mmHg after 20 weeks’ gestation. A birth weight over the 90^th percentile for gestational age indicated large for gestational age (LGA) infants.

Participants were aged a mean 32 weeks and were diagnosed at a mean 25 weeks’ gestation. Delivery occurred at a mean 38 weeks’ gestation, and participants had a mean BMI of 22.8 kg/m² at the first prenatal visit.

Normal fasting glucose levels at the 6-week postpartum visit was reported in 87% of GDM women, vs abnormal fasting glucose levels in 12.5%. Fifty seven percent of the latter group had abnormal fasting glucose levels at GDM diagnosis, which was significantly more common when compared to those with normal fasting glucose levels.

Abnormal 1-hour glucose levels at GDM diagnosis were reported in 55% patients with abnormal postpartum levels vs 47% with normal postpartum levels, indicating no statistically significant differences. Abnormal fasting glucose levels the day before delivery was reported in 64% vs 32%, respectively, indicating a significant difference.

While weekly wight gain and BMI at first prenatal visit did not significantly differ based on postpartum fasting glucose levels, those with abnormal levels were significantly more likely to receive additional insulin treatment during pregnancy, at 9% vs 3.5% in those with normal levels. Rates of delivering an LGA infant were 11% and 5.2%, respectively.

These results indicated an association between fasting glucose levels at GDM diagnosis and postpartum fasting glucose abnormalities. “Our data suggests that fasting glucose levels at diagnosis of GDM could be predictive,” concluded investigators.

References

1. Gu Y, Chen Y, Hu L, et al. Fasting glucose levels at diagnosis and delivery are associated with postpartum glucose abnormalities in GDM women. Arch Gynecol Obstet. 2025. doi:10.1007/s00404-025-07953-4
2. Mugglestone MA. Management of diabetes from preconception to the postnatal period: summary of NICE guidance. BMJ. 2008;336(7646):714–717. doi:10.1136/bmj.39505.641273.AD