Very tight glycemic control does not improve pregnancy outcomes for women with gestational diabetes, according to the findings of a Russian study presented at the Annual Meeting of the European Association for the Study of Diabetes held at Berlin, Germany. Moreover having tighter glycemic targets resulted in a considerably higher proportion of patients requiring insulin therapy.
Current glycemic goals for the management of gestational diabetes vary “because there is scant evidence on [the association between] glucose levels in pregnancy and pregnancy outcomes,” said lead researcher Polina Popova.
The researchers conducted the study to assess the effect of different intensities of glycemic control on maternal and infant health outcomes.
The investigators randomized women in their 8th to 31st week of gestation who met the World Health Organization 2013 criteria for gestational diabetes to very tight glycemic control (fasting plasma glucose < 5.1 mmol/L and < 7.0 mmol/L postprandial) or less tight glycemic control (fasting plasma glucose < 5.3 mmol/L and < 7.8 mmol/L postprandial).
When patients exceeded their plasma glucose targets in two or more measurements per week in the tight control group or more than one-third of measurements per week in the less-tight control group, insulin therapy was started.
The primary outcome of the study was the incidence of large-for-gestational-age infants born to the mothers in the study. Secondary outcomes for the baby were the composite of neonatal death or severe morbidity (ie, nerve palsy, bone fracture, and shoulder dystocia), gestational age at birth, birth weight, macrosomia (birth weight > 4000 g), small for gestational age, and hypoglycemia. Secondary outcomes for the woman were preeclampsia, mode of birth, mean daily fasting and postprandial capillary glucose concentration during treatment, the proportion of glucose values within the target, and the proportion of women requiring insulin therapy.
Overall, 262 women were included in the tight control group and 253 in the less-tight control group. The two groups of women were similar with respect to their ages and prepregnancy body mass index.
Key study findings:
- 32% of 244 patients in the very tight control group met their glucose target, as did 68% of 232 women in the comparison group.
- Additionally, 18% of patients in the comparison group achieved very tight glucose control, while 83% of those aiming for very tight control met the glucose target set for the comparison group.
- There was no significant difference in the primary outcome of proportion of large for gestational age (LGA) infants born to women from the very tight control and the comparison groups, with rates of 14.3% and 16.4%, respectively.
- Similarly, rates of other outcomes including macrosomia, neonatal hypoglycemia, cesarean delivery, and preeclampsia were also comparable between the two groups, as was the average gestational age at birth and birth-weight.
“We expected to find some difference in pregnancy outcomes in the groups with different glycemic control, at least for the frequency of large- and small-for-gestational-age neonates,” said Dr. Popova. These results were somewhat surprising for the investigators.
According to the researchers, very tight glycemic control is associated with the far greater use of insulin therapy as approximately half of the patients in the very tight control group and approximately a quarter of those in the comparison group started insulin during the trial.