(149) Association between postpartum continuous glucose monitoring and oral glucose tolerance testing for screening after GDM

ACOG/ADA recommend diabetes screening after GDM pregnancies; however, only half complete postpartum oral glucose tolerance testing (OGTT). Given high satisfaction with continuous glucose monitoring (CGM) for diabetes management, we aimed to determine the association between postpartum CGM and OGTT.

Study Design:

Prospective observational study of pregnant individuals with GDM who wore a masked Dexcom G6 CGM for 10 days and completed a 75g, 2hr OGTT at 3 study visits postpartum—immediate (< 48hr), 6wk, and 6mo. Participant satisfaction was also surveyed. Using ACOG/ADA criteria, OGTT results were categorized as normal, prediabetes (preDM) or type 2 diabetes (T2DM). Ordinal logistic regression estimated the association between average glucose on CGM and OGTT diagnosis, adjusted for study visit timing and clustering by individual. Secondary outcomes (normal OGTT, T2DM, fasting and 2hr glucose) were analyzed using logistic and linear regression. In sensitivity analyses, we evaluated the association between other CGM metrics and OGTT diagnosis.

Results:

32 participants completed CGM and OGTT at 53 visits (27 immediate, 20 at 6wk, and 6 at 6mo). Average prepregnancy BMI was 35±9kg/m² with 7.5kg gestational weight gain. For every 10mg/dL increase in average glucose on CGM, there was 1.83 times higher odds of preDM or T2DM vs normal GTT and 1.83 times higher odds of T2DM vs normal or preDM (Table). Study visit timing did not modify this effect (interaction p=0.10). With increasing average glucose on CGM there were lower odds of normal OGTT, higher odds of T2DM, and higher fasting and 2-hour glucose levels (Table). While other CGM metrics (TIR, TAR, TBR, and variability) were not associated with OGTT, the % time >250mg/dL was associated with higher odds of preDM or T2DM (aOR 5.63, 95%CI 2.06-15.4). Finally, 87% preferred CGM, 13% had no preference and none preferred OGTT.

Conclusion:

Postpartum average glucose on CGM was associated with OGTT. Validation of these findings and development of diagnostic CGM criteria may provide a more acceptable alternative to postpartum OGTT for diabetes screening after GDM.