Is fasting glucose level during oral glucose tolerance test an indicator of the insulin need in gestational diabetes?

Maintenance of a good metabolic control improves foetal and maternal outcomes in gestational diabetes mellitus (GDM). The aim of this study is to investigate the utility of diagnostic oral glucose tolerance test (OGTT) in prediction of the need of insulin in patients with GDM. One hundred and fifty five consecutive patients with GDM were included in the study. Patients were ordered MNT first. Those who failed to maintain glycemic targets were treated with insulin. Glucose levels obtained from the diagnostic OGTT were evaluated regarding the need of insulin during the rest of pregnancy. Fasting, 1h and 3h post-load glucose levels were significantly elevated in patients who required insulin. Multivariate analysis showed that fasting glucose level on OGTT was an independent predictor for the insulin need. A cut-off value of 105mg/dl had a fair specificity (91.89%) and positive predictive value (80.64%) for the prediction of patients who required insulin during the rest of their pregnancy. Our results suggest that fasting glucose level on OGTT is a predictor of the need for insulin treatment in GDM. A cut-off level of 105mg/dl seems to effectively determine high-risk patients for additional treatment other than MNT in GDM.