Can Fasting or Post-prandial Blood Glucose Monitoring be used as a Method in the Diagnosis of Gestational Diabetes and Predicting its Complications in Patients who Refuse OGTT?

Objective: Gestational diabetes mellitus (GDM) is one of the most common metabolic diseases in pregnancy. Negative news in the media has made the GDM test controversial among patients. We aimed to investigate the usability of fasting blood glucose (FG), HgA1c, and post-prandial 2nd-h blood glucose (PG) instead of an oral glucose tolerance test (OGTT) in the diagnosis of GDM and predict its possible complications. Methods: This retrospective cohort study was conducted among patients admitted to a private hospital in Istanbul between December 2020 and July 2022. In our clinic, patients who refuse OGTT are routinely asked for FG and PG after a normal meal. We also evaluate the HgA1c value. Data of 374 patients were obtained and 150 patients were included in the study after exclusion criteria. Women aged 24–28 weeks who refused OGTT were considered the study group. Patients who accepted OGTT were diagnosed with diabetes before, and FG and PG results could not be reached and were excluded from the study. In addition, patients with a body mass index above 35 were not included in the study. Polyhydramnios and macrosomia, which are common diabetes complications, were evaluated during the follow-up of patients, and these conditions were associated with FG and PG. Results: Due to our results, it was determined that FG was weak and PG was moderately successful in estimating the emergence of abnormal fetal characteristics in pregnant women. When the threshold value of FG was taken as 94 mg/dL, the sensitivity was 43%, and the specificity was 8.8%. When the threshold value of post-prandial blood glucose was taken as 143.5 mg/dL, the sensitivity was 64%, and the specificity was 14% (p<0.05). The HgA1c values of the patients did not show a significant difference between the patients who were diagnosed with polyhydramnios and macrosomia and those who did not. Conclusion: The OGTT is still the most valuable test for the diagnosis of GDM. Women who refuse to do OGTT, especially PG, may be valuable in terms of GDM and its complications. For these patients, more study is needed. ABSTRACT