A retrospective multi-institutional study of treatment for mild gestational diabetes in Japan.

Aims: To determine whether treating mild gestational diabetes mellitus (GDM) is associated with improvement of pregnancy outcomes in Japan.

Methods: In a multi-institutional retrospective study, we examined pregnant women meeting the criteria for mild GDM (i.e., only one abnormal value [OAV] for 75-g OGTT; fasting glucose ≥100 mg/dL, 1-h postprandial glucose ≥180 mg/dL, and 2-h postprandial glucose ≥150 mg/dL), receiving either routine prenatal care (non-treatment group) or dietary intervention alone or dietary intervention with self-monitoring of blood glucose and/or insulin therapy, if necessary (treatment group). Pregnancy outcomes were compared between these groups.

Results: Data from 893 eligible women were collected from 30 institutions. Participants included 542 untreated and 351 treated women. Although there were no significant differences in baseline clinical characteristics or maternal and perinatal outcomes between these groups, the incidence of large-for-gestational-age (LGA) infants was lower in the treatment group (P=0.07). Multiple logistic regression analysis (MLRA) revealed that pre-pregnancy BMI and gestational weight gain were associated with LGA infants, while 75-g OGTT results were unrelated to LGA. When overweight and obese women were the subjects, the number of LGA infants was significantly lower in the intervention than in the control group, and gestational weight gain was significantly lower in the treatment than in the control group. MLRA showed that intervention was significantly related to a lower incidence of LGA infants.

Conclusions: Our study suggests that maternal BMI impacts fetal growth and that treatment for overweight or obese mothers with OAV is associated with a lower frequency of LGA infants.