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. Over-all, 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 ges-tational 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.