Clinical and Investigative Medicine
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Purpose: To determine the associations between glycated hemoglobin (A1C) values at three, 12 and 24 months postpartum taken during the Families Defeating Diabetes trial. Methods: The Families Defeating Diabetes trial was a randomized 12 month lifestyle intervention delivered in the first year postpartum. Women were reviewed at three, 6 12 and 24 months for body habitus, diet and lifestyle choices. Glycated hemoglobin levels were measured at three, 12 and 24 months. Results: There were 170 randomization participants: 89 interventional (INT); and 81 control (CON). Of these 170 participants, 50 INT and 47 CON completed 12-month follow-up and 26 INT and 24 CON completed 24-month follow-up. Study outcomes did not differ between the cohorts. Combined intraclass correlation coefficients for reliability of repeated results showed substantial reliability: 0.74 (95% CI 0.63, 0.83) between three and 12 month A1C; and 0.72 (95% CI 0.51, 0.85) for three and 24 month A1C. Pearson correlations for three month vs 12 month A1C were r=0.745 (p<0.001) and three month vs 24 month A1C were r=0.718 (p=0.001) Conclusions: The A1C values at three, 12 and 24 months after gestational diabetes mellitus showed substantial reliability by intraclass correlation coefficients analysis as well as significant Pearson correlations. These findings add perspective to timing and use of A1C to document postpartum glucose tolerance for women with recent gestational diabetes mellitus. These findings suggest a role for postpartum A1C testing; however, a longitudinal comparison with OGTT results is required to confirm clinical validity.