Diagnosis of gestational diabetes mellitus using a modified 100 g oral glucose tolerance test

To determine an optimal cutoff level of a modified 100 g oral glucose tolerance test (OGTT) with its diagnostic performance for gestational diabetes mellitus (GDM).

Obstetric records of 909 women who had undergone a 100 g OGTT were reviewed. A modified 100 g OGTT referred to a test using a summation of 1 and 2 h plasma glucose levels after 100 g glucose ingestion. The sensitivity and specificity of this summed glucose at various cutoff levels for diagnosing GDM were obtained. A receiver operating characteristic curve was then constructed to determine the optimal value for a GDM diagnosis.

Based on a conventional 100 g OGTT, GDM was detected in 155 women (17.1%). Using a modified 100 g OGTT, the optimal summed glucose value for GDM diagnosis was > or =341 mg 100 ml(-1) which yielded 93.5% sensitivity and 95.2% specificity.

The modified 100 g OGTT demonstrated high diagnostic performance for GDM, with advantages over a conventional 100 g OGTT in terms of less time consuming, lower cost and fewer number of venipuncture.