Association Between Glycemia, Glycemic Variability, and Pregnancy Complications in Early GDM

OBJECTIVE: To investigate the association of timing of commencing glucose management with glycemia, glycemic variability, and pregnancy outcomes among women with early gestational diabetes mellitus (GDM). RESEARCH DESIGN AND METHODS: In this substudy among participants of a trial of immediate vs. delayed treatment of early GDM diagnosed by 2013 World Health Organization criteria, all women treated immediately and those with delayed diagnosis at 24-28 weeks' gestation (treated as if late GDM) were instructed to monitor capillary blood glucose (BG) four times a day (fasting and 2-h postprandial) until delivery. Optimal glycemia was defined as ≥95% of BG measurements between 70 and 140 mg/dL (3.9-7.8 mmol/L). RESULTS: Overall, 107,716 BG values were obtained from 329 of 549 (59.9%) women (mean age 32.3 ± 4.9 years, BMI 32.0 ± 8.0 kg/m2, 35% European, gestation at GDM diagnosis 15.2 ± 2.4 weeks). Women treated early (n = 213) showed lower mean glucose (MG) and mean fasting glucose (MFG) compared with those treated late (n = 116) (MG: 5.7 ± 0.4 vs. 5.9 ± 0.5, P < 0.001; MFG: 5.2 ± 0.3 vs. 5.3 ± 0.4, P = 0.004), with greater optimal glycemia (74.6% vs. 59.5%, P = 0.006) and similar glycemic variability. MG was similar from 30 weeks' gestation. Overall, optimal glycemia was achieved in 69% of women and associated with lower birth weight, fewer large-for-gestational-age infants (14.4% vs. 26.7%, P = 0.01), more small-for-gestational-age infants (15.3% vs. 5.9%, P = 0.02), and lower gestational weight gain (4.9 ± 6.4 vs. 7.6 ± 6.2 kg, P = 0.001). Suboptimal glycemia was associated with non-European ethnicity, prior GDM, 1-h glucose at booking oral glucose tolerance test, and insulin use. CONCLUSIONS: Both early and delayed treatment of early GDM resulted in similar glycemia toward the end of pregnancy. Early treatment was associated with improved glycemia overall.