Comparing the first trimester and second trimester fifty grams oral glucose tolerance test values in gestational diabetes mellitus

INTRODUCTION: The present study aimed to assess the results of pregnant women who have been applied a 50 g oral glucose tolerance test (OGTT) in the first and second trimesters and investigate this method’s role in the diagnosis of gestational diabetes mellitus (GDM) and risk factors associated with this disease.
METHODS: This retrospective study was performed on 153 pregnant women who were admitted to our hospital’s antenatal clinics between March 2011 and August 2011. Fifty grams OGTT was applied to the same pregnant women both in the 1st trimester (between 8th and 14th weeks) and second trimester (between 24th and 28th weeks); values of the test results were then compared. A 100 g OGTT diagnostic test was performed on those with a 50 g OGTT value of ≥140 mg/dl in both trimesters. The study patients were divided into two groups as non-GDM and GDM based on venous plasma glucose values measured 1 h after 50 g of oral glucose load given. The non-GDM group consisted of those with plasma glucose levels <140 mg/ dl and plasma glucose levels between 140 mg/dl and 200mg/dl, GDM group plasma glucose levels ≥200 mg/dl. First trimester and second-trimester OGTT values and possible risk factors for GDM (age, gravida, parity, number of abortions, smoking, a previous GDM history, etc.) were compared between non-GDM and GDM groups.
RESULTS: GDM, diagnosed in 4.5% (7) in the first trimester (between 8th and 14th weeks) and 6.5% (10) second trimester, was detected in 11% (17) of 153 pregnant women in the present study. GDM, diagnosed in 41.2% (7 patients) in the first trimester and 58.8% (10 patients) second trimester, was found with a higher rate in pregnant women over 30 years (p=0.000 <0.05). The mean fasting blood glucose (FBG) level was 96 mg/dl in the GDM group and 83 mg/dl in the non-GDM group, with a statistically significant difference, which existed (p<0.05). The mean 50 g OGTT value was 170 mg/ dl in pregnant women diagnosed with GDM in the first trimester, and it was 140 mg/dl in those diagnosed in the second trimester, with this difference was considered statistically different (p<0.05). Age, parity, a family history of DM, FBG, a previous GDM history, gravida, a previous macrosomia history, and a previous history of preeclampsia
were determined as risk factors that significantly increase the risk of GDM (p<0.05). The half of patients was diagnosed with GDM in the early period of pregnancy. In the present study, 41.2% of cases were diagnosed in the first trimester and 58.8% in the second trimester. In general, the patients diagnosed in the first trimester were those being under risk in terms of GDM. According to the present study, it is recommended that the pregnant women should be scanned for GDM in the early period.
DISCUSSION AND CONCLUSION: With screening tests to be applied to risky groups in early pregnancy, a significant number of cases with GDM recently be detected on time. Thereby, maternal and fetal morbidity and mortality rates might be considerably reduced thanks to providing proper treatments and regular monitoring. Furthermore, for obtaining specific data concerning the factors with potential influence on the risk of GDM, further studies on this topic need to be performed.