Effects of gestational diabetes in early pregnancy

This study compared the outcomes of women diagnosed with gestational diabetes mellitus (GDM; diabetes first appearing in pregnancy) who were diagnosed before 24 weeks of pregnancy with those diagnosed after 24 weeks. The study concluded that earlier diagnosis was associated with lower rates of excess weight gain, higher blood glucose levels, greater need for drug-treatment, and higher rates of macrosomia (larger than average birth weight).

The prevalence of GDM is increasing, but the best time to test pregnant women for GDM is uncertain.  The likelihood of developing GDM increases as pregnancy progresses, but some women may develop GDM in the first trimester. Higher blood glucose levels in the first trimester may increase the risk of complications, like macrosomia.

The medical records of 1,369 women with GDM were examined. 167 were diagnosed before 24 weeks, and 1,202 were diagnosed after 24 weeks.

Women with an earlier diagnosis were older, less likely to have a college education or private health insurance, and less likely to be having their first child. Women with an early diagnosis were more likely to be obese, to have high blood pressure, and to have had GDM before.

Women with an early diagnosis were less likely to have excess weight gain during pregnancy. Women diagnosed before 24 weeks had higher glucose levels at diagnosis and for the rest of the pregnancy. 33.5% of women diagnosed before 24 weeks had their HbA1c tested (average blood glucose over the last 3 months), compared to 5.3% of women diagnosed later. HbA1c values were similar between the two groups.

Women with an early diagnosis were more likely to need drug treatment. 64.8% of women diagnosed before 24 weeks were treated with glyburide, compared to 56.2% of those diagnosed later. 19.4% of those diagnosed early were treated with insulin, compared to 6% of those diagnosed later.

Women diagnosed early were twice as likely to have a child with macrosomia. The risk was 2.3 times higher in women treated with glyburide who were diagnosed early compared to women diagnosed later. There were no other complications associated with earlier diagnosis.

The study concluded that women with an earlier diagnosis of GDM were less likely to gain excess weight, had higher blood glucose levels in pregnancy, and were more likely to need drug-treatment. It also found that their children were more likely to have macrosomia.

This study examined medical records, which do not contain all of the relevant information. For example, the researchers did not have data on testing after pregnancy.