LAS VEGAS – There was no difference in first neonatal glucose level or glucose levels within the first 24 hours of life when women with gestational diabetes received strict, rather than liberalized, glucose management in labor.
In a study of 76 women with gestational diabetes mellitus (GDM), the mean first blood glucose level was 53 mg/dL for neonates born to the 38 mothers who received tight glucose control during labor; for those born to the 38 women who received liberalized control, mean first glucose level was 56 mg/dL (interquartile ranges, 22-85 mg/dL and 27-126 mg/dL, respectively; P = .56).
Secondary outcomes tracked in the study included the proportion of neonates whose glucose levels were low (defined as less than 40 mg/dL) at birth. This figure was identical in both groups, at 24%.
These findings ran counter to the hypothesis that Maureen Hamel, MD, and her colleagues at Brown University, Providence, R.I., had formulated – that neonates whose mothers had tight intrapartum glucose control would have lower rates of neonatal hypoglycemia than those born to women with liberalized intrapartum control.
Although the differences did not reach statistical significance, numerically more infants in the tight-control group required any intervention for hypoglycemia (45% vs. 32%; P = .35) or intravenous intervention for hypoglycemia (11% vs 0%; P = .35). Neonatal ICU admission was required for 13% of the tight-control neonates versus 3% of the liberalized-control group (P = .20).
“A protocol aimed at tight maternal glucose management in labor, compared to liberalized management, for women with GDM, did not result in a lower rate of neonatal hypoglycemia and was associated with mean neonatal glucose closer to hypoglycemia [40 mg/dL] in the first 24 hours of life,” said Dr. Hamel, discussing the findings of her award-winning abstract at the meeting presented by the Society for Maternal-Fetal Medicine.
Women were included if they were at least 18 years old with a singleton pregnancy and a diagnosis of gestational diabetes. Participants received care through a specialized program for pregnant women with diabetes; they were considered to have GDM if they had at least two abnormal values from a 100-g, 3-hour glucose tolerance test (GTT) or had a blood glucose reading of at least 200 mg/dL from a 1-hour 50-g GTT. About two-thirds of women required medical management of GDM; about 80% received labor induction at 39 weeks’ gestation.
At 36 weeks’ gestation, participants were block-randomized 1:1 to receive tight or liberalized intrapartum blood glucose control, with allocation unknown to both providers and patients until participants were admitted for delivery. Neonatal providers were blinded as to allocation throughout the admission. “In the tight glucose control group, point-of-care glucose was assessed hourly,” said Dr. Hamel. “Goal glucose levels were 70-100 [mg/dL], and treatment was initiated for a single maternal glucose greater than 100 and less than 60 [mg/dL].”
Those in the liberalized group had blood sugar checked every 4 hours in the absence of symptoms, with a goal blood glucose range of 70-120 mg/dL and treatment initiated for blood glucose over 120 or less than 60 mg/dL.
The increase in older women giving birth partly underlies the increase in GDM, said Dr. Hamel. By 35 years of age, about 15% of women will develop GDM, compared with under 6% for women giving birth between 20 and 24 years of age.
Neonatal hypoglycemia, with associated risks for neonatal ICU admission, seizures, and neurologic injury, is more common in women with GDM, said Dr. Hamel, a maternal-fetal medicine fellow.
There’s wide institutional and geographic variation in intrapartum maternal glucose management, said Dr. Hamel. Even within her own institution, blood sugar might be checked just once in labor, every 2 hours, or every hour, and the threshold for treatment might be set at a maternal blood glucose level over 100, 120, or even 200 mg/dL.
The study benefited from the fact that there was standardized antepartum GDM management in place and that 100% of outcome data were available. Also, the a priori sample size to detect significant between-group differences was obtained, and neonatal providers were blinded as to maternal glucose control strategy. Replication of the study should be both easy and feasible, said Dr. Hamel.
However, only very short-term outcomes were tracked, and the study was not powered to detect differences in such less-frequent neonatal outcomes as neonatal ICU admission.
“There is no benefit to tight maternal glucose control in labor among women with GDM,” concluded Dr. Hamel. “Our findings support glucose assessment every 4 hours, with intervention for blood glucose levels less than 60 or higher than 120 [mg/dL].”
Dr. Hamel reported no outside sources of funding and no conflicts of interest.
SOURCE: Hamel M et al. .