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Stricter Treatment Targets for Gestational Diabetes Leads to Earlier Births, No Difference in Birth Weight

Dec 8, 2018
 
Editor: Steve Freed, R.PH., CDE

Author: Clarke Powell, Pharm.D. Candidate 2019, LECOM School of Pharmacy

New study shows implementing tighter treatment goals for GDM does not improve birth weight in neonates, but may increase risk for earlier birth and clinician intervention.

A new study published in Diabetic Medicine revealed that tighter treatment targets for gestational diabetes showed no difference in primary birth weight outcomes, despite greater insulin use. To the knowledge of the investigators of the study, no randomized controlled trials comparing differing glycemic targets on pregnancy outcomes are currently available. The goal of this study was to examine the outcomes associated with standard treatment compared to tighter treatment goals in gestational diabetes mellitus (GDM).

A large-scale observational cohort was conducted in two Australian hospitals examining singleton births greater than 28 weeks gestation to mothers with GDM. Women with pre-existing type 1 or type 2 diabetes were excluded from the trial.

Two groups were established with different treatment targets: The first group (Service One) applied standard targets with fasting <5.5mmol/l and 2-hour postprandial <7.0mmol/l. The second group (Service Two) had tighter targets of fasting <5.0mmol/l and 2-hour postprandial <6.7mmol/l. Each woman self-monitored fasting and 2-hour postprandial glucose levels and insulin was administered if two or more levels exceeded targets in one week.

Primary neonatal outcomes for the trial were birth weight >90th percentile and <10th percentile for both age and sex. Secondary outcomes were hypoglycemia, considered <2.6mmo/l, clinical jaundice, respiratory distress, and Apgar score <7 at 5 minutes. Maternal outcomes were considered gestational hypertension and pre-eclampsia. Practice outcomes for the trial were given by mode of birth, including cesarean section and pre-term birth <37 weeks.

Statistical analysis included descriptive statistics for maternal characteristics, chi-square tests for categorical data, and both t-tests and Mann-Whitney U-tests to compare continuous data.

A total of 4,785 women with GDM were included in the results analysis (2,891 at Service One, and 1,894 at Service Two). Primary results showed that babies of mothers exposed to tighter treatment targets were born more than 1 week earlier on average (38 weeks vs. 39.1 weeks) though did not differ in birth weight compared to standard treatment. Maternal outcomes also did not differ between treatment groups, with no difference in risk of gestational hypertension or pre-eclampsia.

Some interesting results when assessing secondary neonatal outcomes showed that tighter treatment targets led to decreased risk of hypoglycemia, jaundice, and respiratory distress, but gave increased risk of Apgar scores >7 at 5 minutes compared to the standard treatment target group. Additionally, mothers with tighter treatment targets saw an increase in both inductions of labor and caesarean section, though there was no significant difference in NICU admission or preterm birth.

This being the largest epidemiological study on GDM treatment targets to date, the results give compelling insight into the impact of differing treatment plans for GDM. While tighter treatment goals showed no differences in the birth weights >90th percentile and <10th percentile compared to standard treatment targets, tighter targets did display an increase in insulin use, earlier births, and higher rates of clinician intervention. While investigators did observe lower risk for hypoglycemia, jaundice, and respiratory distress in the neonates of tighter treatment targets, much is to be said regarding the aforementioned outcomes.

Overall, it is safe to say that stricter treatment goals for GDM cannot, and should not, be implemented into practice solely to ensure better neonatal and maternal outcomes. With the lack of assurance that tighter treatment goals provide any additional benefit, standard treatment targets should continue to be utilized until more sufficient evidence is discovered.

Practice Pearls:

  • Tighter treatment targets for GDM were not associated with differences in birth weight in neonates compared to standard treatment goals.
  • Tighter treatment targets led to decreased risk of hypoglycemia, jaundice, and respiratory distress, but gave increased risk of Apgar scores >7 at 5 minutes compared to the standard treatment target group.
  • Use of tighter treatment targets displayed an increase in insulin use, earlier births, and higher rates of both labor induction and caesarean section compared to standard treatment targets.

Reference:

Abell, S. K., Boyle, J. A., Earnest, A., England, P., Nankervis, A., Ranasinha, S., Teede, H. J. (2018). Impact of different glycaemic treatment targets on pregnancy outcomes in gestational diabetes. Diabetic Medicine. doi:10.1111/dme.13799

Clarke Powell, Pharm.D. Candidate 2019, LECOM School of Pharmacy