Evaluation of 75 g glucose load in non-fasting state [Diabetes in Pregnancy Study group of India (DIPSI) criteria] as a diagnostic test for gestational diabetes mellitus.

Background & Objectives: There is no consensus regarding optimal standard for diagnosis of gestational diabetes mellitus (GDM). In this study, use of 75 g glucose load in non-fasting state [Diabetes in Pregnancy Study Group of India (DIPSI) criteria] as a diagnostic test for GDM in pregnant women was compared with different oral glucose tolerance tests (OGTTs).

Methods: This prospective study included 936 pregnant women, who underwent plasma glucose evaluation two hours after the challenge of 75 g glucose load irrespective of the timing of last meal (DIPSI criteria for GDM). After three days, standard 75 g OGTT was done in all women irrespective of previous plasma glucose value. Accuracy of the first result was compared to OGTT using cut-offs as per the World Health Organization (WHO) and International Association of Diabetes and Pregnancy Study Groups (IADPSG) criteria for the diagnosis of GDM.

Results: Of the total 936 pregnant women, 73 (7.8%) patients had plasma glucose value ≥140 mg/dl when measured two hours after glucose load. When comparing with the WHO and IADPSG criteria, the sensitivity values were 65.1 and 74.1 per cent, respectively, and the corresponding specificity values were 96.3 and 96.9 per cent, respectively. On comparing with the WHO OGTT, only 41 of the 73 (56.2%) were true positives, whereas when IADPSG criteria were used, true positives were 46 (63%). False negative cases were also present when classified by the WHO and IADPSG criteria though in lesser numbers than false positives. The positive predictive values (PPVs) for the WHO and IADPSG criteria were 56.1 and 63 per cent, respectively, and their corresponding negative predictive values were 97.7 and 97.9 per cent, respectively.

Interpretation & Conclusions: Our findings showed that when 75 g glucose load in non-fasting state was used as a diagnostic test for GDM, almost one quarter of patients with GDM escaped diagnosis as sensitivity values were low. On the other hand, some GDM cases were falsely labelled as normal as this test did not account for cases of fasting hyperglycaemia. In addition, comparison with other OGTTs showed low PPVs. Hence, use of DIPSI criteria for diagnosing GDM must be reconsidered till further validation.