To the Editor We were prompted by the increasing prevalence of gestational diabetes and widespread obstetric use of oral sulfonylureas to read with interest the retrospective analyses by Camelo Castillo et al.1,2 From an employer-based insurance database, Camelo Castillo and colleagues confirmed reports of others that infants born to women treated with glyburide are at increased risk for being large for gestation age and having hypoglycemia, both potential markers of fetal and neonatal hyperinsulemia.3 The authors also found these infants exposed to glyburide during the fetal period were at increased risk for birth injury. While the relationship between large for gestation age and birth injury is clearly understandable, the authors did not address the confounding health care professional variability in the glyburide group as it relates to obstetric surgical intervention and lower cesarean and episiotomy rates. The decision to perform a cesarean is often not based on objective evidence, but driven primarily by the health care professional’s own experience or anecdotal data.4 A health care professional may consider the use of insulin rather than glyburide as a marker for disease severity and, therefore, an indication for cesarean delivery. During the study period, 2000 to 2011, health care professionals in the United States chose to perform fewer episiotomies; once again, we suggest this invokes the variable of health care professional choice affecting the outcome of interest, birth injury.5 While we agree with the authors that use of glyburide during pregnancy may be problematic, the higher rates of birth injury associated with glyburide may not be directly related to this hypoglycemic agent, but rather caused by patterns of obstetric surgical intervention during the study period.
Rezai S, Vielman M, Henderson CE. Glyburide vs Insulin and Adverse Pregnancy Outcomes. JAMA Pediatr. 2015;169(10):974-975. doi:10.1001/jamapediatrics.2015.1808