Markers of Glycemic Control and Neonatal Morbidity in High-Risk Insulin-Resistant Pregnancies

Objective This study aims to determine whether fructosamine, glycated hemoglobin A_1C (HbA_1c), or mean fasting glucose levels associate with birth outcomes in diabetic women. Study Design A prospective cohort study of women with singleton, nonanomalous pregnancies and diagnosis of diabetes (gestational or pregestational). Daily average self-measured fasting serum glucose levels were collected, as well as HbA_1c and fructosamine levels at delivery. The primary outcome was neonatal composite morbidity, defined as having one or more of the following: respiratory distress syndrome, hyperbilirubinemia, perinatal death, shoulder dystocia, and hypoglycemia requiring treatment. Secondary outcomes included macrosomia (≥ 4,000 g). Results Among neonates delivered by 301 study-eligible women (97 with gestational and 204 with pregestational diabetes), incidences of composite morbidity (n = 147, 48.8%) and macrosomia (n = 49, 16.3%) were high. Macrosomia occurred more frequently in infants of pregestational than gestational diabetic mothers (22.7 vs. 13.2%, p = 0.04), composite morbidities were not significantly different (52.2 vs. 42.3%, p = 0.14). HbA_1c > 8.0 significantly increased risk of morbidity and macrosomia (relative risk, 4.29; 95% confidence interval, 1.62-11.3). Conclusions Late third-trimester HbA_1c, but not fructosamine or mean blood glucose levels, was associated with increased morbidity in infants of diabetic mothers. Third-trimester HbA_1c could be clinically useful for counseling regarding neonatal risks in women with diabetes.