Background: The optimal timing for detecting and initiating treatment for gestational diabetes mellitus (GDM) remains a topic of debate and is largely understudied. Neonates born to women with GDM continue to experience metabolic and other complications despite receiving treatment from 24 weeks’ gestation (weeks’). This study investigates the association of timing of commencing glucose management with glycaemia, glycaemic variability, and pregnancy outcomes among women with GDM diagnosed before 20 weeks’ (early GDM - eGDM).
Methods: This is a sub-study among participants of a trial of immediate vs delayed treatment of eGDM diagnosed by WHO-2013 criteria. All women treated immediately and those with delayed treatment following a reconfirmation of diagnosis at 24-28 weeks’ (i.e., treated as if late GDM) were instructed to monitor capillary blood glucose (BG) using an Accu-Chek Guide (Roche Products Ltd, Sydney, Australia) glucose meter 4 times/day (fasting and 2-h post-prandial), up-loading values to the Accu-Chek web-portal, until delivery. Optimal glycaemia was defined as ≥95% of BG measurements between 3.9-7.8 mmol/l. Meter data were later downloaded from the web-portal. Times of testing data were unavailable.
Results: Data from six sites (n=114) were not available for technical reasons. Overall, 107,716 BG values were obtained from 329/549 (59.9%) women with eGDM (mean age 32.3±4.9 years, Body Mass Index (BMI) 32.0±8.0 kg/m2 ethnicity 35% European, gestation at eGDM 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 glycaemia (74.6% vs. 59.5%, p=0.006). Overall, optimal glycaemia was achieved in 69% of women: this was associated with lower birthweight (3.2±0.5 vs. 3.3±0.5kg, p=0.04), less large-for-gestational-age (LGA) babies (14.4% vs. 26.7%, p=0.01) more small-for-gestational-age (SGA) babies (15.3% vs. 5.9%, p=0.02) and less gestational weight gain (GWG)(4.9±6.4 vs. 7.6±6.2, p=0.001). Prior GDM, 1-hour glucose at booking oral glucose tolerance test (OGTT), and greater GWG were associated with suboptimal glycaemia. Higher MFG (5.2-5.3 mmol/l) in the second trimester was associated with more respiratory distress, whereas, when present in the third trimester, MFG ≥5.4 mmol/l was associated with more LGA babies and earlier gestation at birth. Booking BMI, fasting glucose at booking OGTT, and GWG were significant predictors of MFG ≥5.4 mmol/l.
Conclusions: Early commencement of treatment in women with eGDM resulted in improved glycaemia which was associated with reduced fetal overgrowth.