Effectiveness of Continuous Glucose Monitoring in Pregnant Women With Diabetes: Randomized Clinical Trial

Abstract

Near optimal control of glucose levels during early pregnancy has not reduced the risk of macrosomia among infants of women with type 1 or 2 diabetes. Observational data suggest a strong correlation in the third trimester between maternal postprandial glucose levels and increased risk of macrosomia. The effectiveness of long-term glycemic control in reducing diabetes related morbidity in pregnant women is unclear. This prospective, open label randomized controlled trial evaluated the effectiveness of antenatal continuous glucose monitoring on maternal glycemic control and risk of macrosomia in patients with type 1 and 2 diabetes at 2 diabetic antenatal clinics between 2003 and 2006. A total of 71 pregnant women aged 16 to 45 with type 1 (n = 46) or type 2 diabetes (n = 25) were allocated to either antenatal care using intermittent monitoring of capillary blood glucose supplemented with continuous glucose monitoring (n = 38) or to standard antenatal care using intermittent self monitoring of glucose levels (n = 33). Continuous glucose monitoring was provided for up to 7 days at intervals of 4 to 6 weeks from 8 to 32 weeks of gestation. There were no other differences in antenatal care of the 2 study groups. Compared with women randomized to standard antenatal care (control group), women randomized to continuous glucose monitoring (intervention group) had lower mean HbAlc levels at 32 to 36 weeks' gestation: 6.4% (SD, 0.7) versus 5.8% (SD, 0.6), respectively, P = 0.007. The mean birth weight standard deviation scores of singletons of women in the intervention group were lower than those of healthy singletons of women in the control group (0.9 vs. 1.6; effect size 0.7 SD, 95% confidence interval [CI], 0.0-1.3; P = 0.05). The median birth weight centiles were significantly lower: 69% in the intervention group compared with 93% in the control group (P = 0.02). Thirty-five percent of the infants in the intervention group were macrosomic compared to 60% in the control group (odds ratio, 0.36; 95% CI, 0.13-0.98; P = 0.05). These findings suggest that supplementary continuous glucose monitoring during routine antenatal care can improve glycemic control in pregnant women with diabetes and reduce the risk of macrosomia among their infants.