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CME Credit Offered
CME Credit Offered
Abstract Award
Abstract Award
Recording available 2/16-5/2
Recording available 2/16-5/2
AIUM Credit
AIUM Credit
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Foundation Awardee
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Abstract Award
Abstract Award
Foundation Awardee
Foundation Awardee

Poster Session 1

Category: Diabetes

Poster Session 1

(223) Continuous Glucose Monitoring (CGM) During 1-hour Oral Glucose Tolerance Testing (OGTT)

Wednesday, February 11, 2026
10:30 AM - 12:00 PM  
Objective:
Although it is the standard approach to the diagnosis of gestational diabetes (GD), the oral glucose tolerance test (OGTT) has many disadvantages. Continuous glucose monitors (CGMs) may circumvent those disadvantages. A study was designed to examine the diagnostic utility of 7-10 days of CGM wear prior to the OGTT. The main objective of this secondary analysis was to explore what CGMs reveal about glucose dynamics during the OGTT.

Study Design:
Gravidas without pre-existing diabetes at 24-28 weeks wore a blinded Dexcom G6 CGM prior to and during the 1-hour OGTT. For this analysis of CGM readings during the OGTT, the outcomes were 1) screen positive OGTT (1-hour blood glucose [BG] ≥ 130 mg/dL) and 2) subsequent diagnosis of GD. CGM glucose and venous BG at 60 minutes were also compared.

Results:
Of 75 study participants, 27 (36%) had a positive OGTT and 6 (8%) were diagnosed with GD.  Mean glycemic excursion on CGM during the 1-hour OGTT was 11.5 mg/dL higher in the screen-positive group vs the screen-negative group (p = 0.02) and 13.6 mg/dL higher in those with GD vs those without GD (p = 0.06). Five participants (n=2 screen-positive, n=3 screen-negative) were excluded from the 60-minute glucose comparison due to early CGM removal. Compared to venous BG, CGM glucose was 20.3 mg/dL higher on average. CGM correctly identified elevated BG (≥ 130 mg/dL) in 23 out of 25 (92%) screen-positive cases but was incorrectly elevated in 21 out of 45 (47%) of screen-negative cases (p < 0.001). 

Conclusion:
Mean glycemic excursion on CGM worn during OGTT is significantly higher among those who screen positive compared to those who screen negative and substantially higher among those with GD compared to those without GD. Importantly, CGM readings at 60 minutes were significantly higher than venous BG. If CGM is used to screen for or diagnose GD, a higher cutoff value should be utilized to avoid false positives, since CGM readings lag venous BG when BG is decreasing.