Researchers find every 0.1% increase in HbA1c above 5.1% increases diagnosis risk by 22%.
Gestational diabetes is a common complication in pregnancy that carries an increased risk for type 2 diabetes and cardiovascular disease later in life for mothers, as well as an increased risk for macrosomia and obesity in the infant. Due to these reasons, early risk prediction is important to provide a unique opportunity for early interventions. Currently, women are screened for gestational diabetes between weeks 24 and 28 of pregnancy, unless they have a known risk factor (e.g. obesity).
In this Scientific Reports study, researchers used HbA1c testing to see if they could identify signs of gestational diabetes in the first trimester. Only a few studies have examined whether or not HbA1c could be used to examine the risk of gestational diabetes in pregnancy, and the women tested in these studies already have a high risk for the disease.
The HbA1c test is not used to diagnose gestational diabetes at any time during pregnancy. They used a secondary analysis of participants from the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD) Fetal Growth Study that enrolled over 2,000 pregnant women who were low-risk from 12 different U.S. clinical sites between 2009 and 2013. Scientists compared HbA1c results from 107 women who eventually developed gestational diabetes to the HbA1c results from 214 women who did not develop the disease.
A majority of the women had HbA1c levels drawn at four different time intervals during pregnancy: early (weeks 8-13), middle (weeks 16-22 and 24-29) and late (weeks 34-37). Women who later developed gestational diabetes had an average HbA1c of 5.3%, compared to those who never developed the condition who had an average HbA1c of 5.1%. For every 0.1% increase in HbA1c above 5.1% that was retained in earlier pregnancy, researchers found that the patient was associated with a 22% higher chance of developing gestational diabetes.
All of the participants showed similar patterns throughout their pregnancies as their HbA1c decreased slightly during the second trimester and increased in the third. Researchers noted this is due to the high red blood cell turnover during pregnancy and the decrease in insulin sensitivity later in gestation.
“Our results suggest that the HbA1C test potentially could help identify women at risk for gestational diabetes early in pregnancy, when lifestyle changes may be more effective in reducing their risk,” explained Cuilin Zhang, Ph.D., of the Epidemiology Branch at NIH’s Eunice Kennedy Shriver National Institute of Child Health and Human Development.
If health care practitioners are able to identify women at high risk for gestational diabetes early in pregnancy, they can focus on lifestyle changes, such as diet and exercise, to prevent complications from the disease.
Further research is needed to confirm the association between HbA1c levels in early pregnancy and the risk for developing gestational diabetes. Authors also noted that further research is warranted to assess whether lifestyle changes before and during pregnancy could help reduce the risk of gestational diabetes.
- There are only a few studies that have examined the relationship between HbA1c and gestational diabetes.
- Researchers found that for every 0.1% increase in HbA1c above 5.1% that was retained in earlier pregnancy, there was a 22% higher chance of the patient developing gestational diabetes.
- If health care practitioners are able to identify women at high risk for gestational diabetes early in pregnancy, they can focus on lifestyle changes, such as diet and exercise, to prevent complications from the disease.
Stefanie N. Hinkle et al. HbA1c Measured in the First Trimester of Pregnancy and the Association with Gestational Diabetes, Scientific Reports (2018). DOI: 10.1038/s41598-018-30833-8
Melissa Bailey, Pharm.D. Candidate, USF College of Pharmacy