A framework to classify gestational diabetes diagnosed by routine antenatal 75g glucose tolerance testing

Objective: To create an objective framework to classify gestational diabetes mellitus diagnosed by routine antenatal 75 g diabetes testing results to provide an alternative to current treatment-based classification. Methods: A framework was created to classify gestational diabetes according to the severity of glycemic abnormalities after routine antenatal 75 g GTT (classes 1 through 4, determined by fasting and post-test glycemic abnormalities). A retrospective cohort chart review was used to correlate clinically how often diet therapy alone maintained glycemic targets throughout pregnancy in each class. Chi-square analysis was used to assess inter-class differences in the success of diet therapy alone maintaining glycemic targets throughout pregnancy. Results: Seventy-four of 228 (33%), 35/228 (15%), 76/228 (33%), and 43/228 (19%) of the study population were classified as Class 1, 2, 3, or 4, respectively. Of eighty-nine patients who maintained glycemic targets throughout pregnancy with diet alone 51/89 (57%) were Class 1, 20/89 (22.5%) were Class 2, 11/89 (12.5%) were Class 3, and 7/89 (8%) were Class 4. Chi-square analysis showed statistically significant inter-class differences in the likelihood of diet therapy alone maintaining glycemic targets throughout pregnancy. Conclusion: In this framework classifying gestational diabetes according to the severity of glycemic abnormalities after routine antenatal 75 g GTT (an objective proxy for disease severity), the higher the assigned class, the less likely that diet therapy alone maintained glycemic targets throughout pregnancy (a clinical proxy for disease severity).