Gestational diabetes: Examining predictors of pregnancy outcomes and future diabetes risk

When a women without diabetes develops high blood glucose levels during pregnancy this is known as gestational diabetes mellitus (GDM). GDM is generally associated with few symptoms. However, it does greatly increase a number of complications, such as preeclampsia, abnormally high birth weight, and the need for a cesarean section. The mother is also at increased risk of developing diabetes later in life. More studies are needed to identify predictors of pregnancy outcomes and long-term prognoses in women who experienced GDM.

The aim of this study was to examine factors that may impact pregnancy outcomes following GDM and the mother’s future risk of developing diabetes.

2,085 GDM pregnancies were included in this study. These were compared to 3,792 non-GDM pregnancies, matched for day of delivery and treatment location. All women were medically screened at the beginning of the pregnancy. Blood glucose levels were recorded at various time points. GDM pregnancies were followed for 8.5 to 13.5 years with a questionnaire that was answered by 65% of women.

GDM pregnancies resulted in significantly higher average infant birth weight (3682 grams) compared to non-GDM pregnancies (3541 grams). 8.3% of infants from a GDM pregnancy were abnormally heavy (weighing 4500 grams or more). This was significantly greater compared to non-GDM pregnancies (3.9% of infants).

Higher blood glucose levels at GDM diagnosis were associated with higher birth weight. Later week of gestation and higher body mass index (excess weight according to height) were also associated with higher birth weight.

At follow-up, 25% of GDM women reported that they had developed diabetes after delivery. Of these, 14% had type 1 diabetes, 65% had type 2 diabetes, and 21% were unclassified diabetes.

Higher blood glucose level at GDM diagnosis were associated with a significantly increased chance of developing diabetes. For instance, women with a fasting blood glucose level of 6.1 mmol/l or more at diagnosis were 8.8 times more likely to develop diabetes compared to women with a level of 4.5 mmol/l or less. Other risk factors of diabetes included higher body mass index and non-European nationality.

Researchers concluded that higher fasting blood glucose levels at GDM diagnosis significantly increased the risk of higher infant birth weight and maternal diabetes risk.

Screening programs for GDM likely varied across treatment centers.