Gestational Diabetes Exposure Contributes to Obesity in Adolescents

Exposure to gestational diabetes mellitus (GDM) in utero may contribute to obesity in youth, according to research published online August 25, 2014, in Diabetologica.

An international team of researchers studied 255 obese adolescents with normal glucose tolerance (NGT) who were aged between 4 and 20 years and recruited from Yale University’s “Study to Investigate Pathophysiology of Type 2 Diabetes in Youth.” Each patient was examined for exposure to GDM and tested for glucose tolerance using the Oral Glucose Tolerance Test at baseline, as well as after an average of 2.8 years.

The participants were separated into 2 groups based on GDM exposure history: not exposed to GDM (NGDM) (82.3%) and exposed to GDM (EGDM) (17.7%). Both groups were similar with respect to age, sex, ethnicity distribution, and body mass index (BMI). Birth weight was also comparable between the 2 groups, even though participants in the EGDM group were, by definition, exposed to GDM in utero.

At follow-up, nearly all of the NGDM patients (91.4%) had NGT levels, and only 8.6% had impaired glucose tolerance (IGT) or type 2 diabetes mellitus (T2DM) and were considered progressors. From this group, 176 patients maintained normal fasting glucose (NFG) throughout the follow-up observations, but 34 (16%) had impaired fasting glucose (IFG).

Fewer patients in the EGDM group had NGT at follow-up (68.9%), while 31.1% developed IGT or T2DM. Of those patients, 32 maintained NFG and 13 developed IFG by the follow-up testing session. Notably, 12 participants with IGT and T2DM combined at follow-up also had IFG.

The researchers noted the 17.7% exposure rate to GDM they found was consistent with the 18% rate reported by the International Association of Diabetes and Pregnancy Study Groups (IADPSG). The IADPSPG studies, however, found differences between NGDM and EGDM birth weights that the current study did not.

“Alarmingly, 31.1% of obese children with NGT who were exposed to GDM in utero developed IGT (in combination with) diabetes over a relatively short follow-up period of <3 years, on average,” the researchers wrote. “Our results show that offspring of mothers who had GDM in pregnancy had at least a 5 times greater risk of developing IGT than those not exposed to GDM.”

The researchers also noted that the EGDM group demonstrated decreased insulin sensitivity over time, which they attributed to beta cells’ inability to increase insulin secretion, as well as the body’s resulting inability to compensate for a decrease in insulin.

“While we cannot use this analysis for development of definitive screening guidelines, we strongly suggest that, among obese children and adolescents exposed to GDM…(glucose tolerance tests) should be performed at baseline—specifically in mid-pubertal adolescents&mdash;and potentially repeated based on clinical judgment,” the researchers recommended in their conclusion.