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Tight targets for gestational diabetes fail to improve birth weight, maternal outcomes
Stricter treatment targets for gestational diabetes were associated with greater insulin use, but no difference in primary birth weight or maternal outcomes, according to findings from a comprehensive large-scale cohort study published in Diabetic Medicine.
“Tight treatment targets in gestational diabetes mellitus are currently not evidence-based. Here, outcomes in clinical services with tight targets were compared to those with standard targets, with no differences in primary birth weight outcomes, yet with higher insulin use, earlier delivery and higher induction and cesarean section rates,” Helena Teede, MBBS, FRACP, PhD, an endocrinologist and director of Monash Centre for Health Research Implementation, School of Public Health, Monash University in Australia, told Endocrine Today. “Secondary outcomes varied and were likely impacted by mode of delivery.”
Teede and colleagues evaluated the outcomes of singleton births delivered at 28 weeks’ gestation or older at one of two major maternity services in Victoria, Australia, from 2009 to 2013. Both services asked women with gestational diabetes to monitor fasting glucose and 2-hour postprandial glucose after every meal and initiated first-line insulin if two or more glucose levels per time point exceeded targets in 1 week despite dietary intervention. However, the treatment targets differed: Service 1 applied standard targets of less than 5.5 mmol/L for fasting glucose and less than 7 mmol/L for 2-hour postprandial glucose, whereas Service 2 applied tighter targets of less than 5 mmol/L for fasting glucose and less than 6.7 mmol/L for 2-hour postprandial glucose.
Rates of gestational diabetes were 7.9% (n = 2,885) at Service 1 and 5.7% (n = 1,887 women) at Service 2. Insulin therapy was required for 31% of women at Service 1 compared with 46% at Service 2. Women with the tighter treatment targets delivered their babies earlier, at a median of 38 weeks, compared with 39.1 weeks for the women with standard targets (P < .001). However, compared with the standard treatment targets, tighter treatment targets were not associated with a difference in the primary outcomes of birth weight greater than the 90th percentile (adjusted OR = 1.06; 95% CI, 0.87-1.3) or birth weight less than the 10th percentile (aOR = 0.84; 95% CI, 0.7-1.01).
Propensity score analysis revealed no difference between the two services in the risk for gestational hypertension, preeclampsia, shoulder dystocia or the composite perinatal outcome. Compared with babies of those treated at Service 1, babies of women treated at Service 2 with tighter treatment targets had a decreased risk for hypoglycemia (aOR = 0.76; 95% CI, 0.61-0.94), jaundice (aOR = 0.47; 95% CI, 0.35-0.63) and respiratory distress (aOR = 0.68; 95% CI, 0.47-0.98). However, babies of women at Service 2 had an increased risk for Apgar scores less than 7 at 5 minutes (aOR = 1.54; 95% CI, 1.05-2.25).
Data also revealed increased rates of labor induction (aOR = 3.63; 95% CI, 3.17-4.16) and cesarean section (aOR = 1.17; 95% CI, 1.03-1.33), as well as an increased rate of elective cesarean section (aOR = 1.75; 95% CI, 1.37-2.23) at Service 2 compared with Service 1. Service 2 babies had a lower risk for admission to the special care nursery (aOR = 0.32; 95% CI, 0.26-0.38), but there was no difference in preterm birth or admission to the neonatal ICU. Similar differences between Service 1 and Service 2 were observed among women without gestational diabetes.
The researchers noted these differences cannot be clearly attributed to the difference in treatment targets because of variations observed in care at the two services.
“Although a large-scale study, these data are observational and need to be interpreted with caution,” Teede said. “The key clinical message is to be cautious when implementing what has not yet been adequately trialed, and if these [treatment targets] are implemented, be aware of and monitor for potential unintended consequences, such as earlier delivery and higher induction and cesarean section rates.” – by Tina DiMarcantonio-Brown
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Helena Teede, MBBS, FRACP, PhD, can be reached at the Monash Centre for Health Research and Implementation, Monash University, Locked Bag 29, Clayton VIC 3168, Australia; email: helena.teede@monash.edu.
Disclosure: Teede reports she receives competitive funding from the National Health and Medical Research Council.