Comparative Diagnostic Performance of First-Trimester Hba1c and DIPSI For Early Screening of Gestational Diabetes Mellitus: A Prospective Study At A Tertiary Care Centre in Telangana, India

Abstract

Background: Detecting gestational diabetes mellitus (GDM) early in pregnancy may allow earlier risk assessment and management. Although routine screening is commonly performed at 24–28 weeks, glucose abnormalities can be present much earlier. HbA1c is a convenient biomarker that does not require fasting, while the Diabetes in Pregnancy Study Group India (DIPSI) approach is a simple non-fasting test used widely in India. This study assessed and compared the performance of first-trimester HbA1c and DIPSI using the 75-g oral glucose tolerance test (OGTT) as the reference method.

Methods: This prospective observational comparative study included pregnant women attending a tertiary teaching hospital in Telangana during the first trimester. Eligible participants underwent HbA1c measurement, DIPSI testing, and a 75-g OGTT. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), overall diagnostic accuracy, and agreement between the screening tests were evaluated.

Results: One hundred women were enrolled. The mean HbA1c was 5.42 ± 0.62%, and the mean 2-hour plasma glucose was 126.8 ± 28.5 mg/dL. The reference OGTT diagnosed GDM in 16% of participants. HbA1c classified 19% as screen-positive and had a sensitivity of 81.3% and specificity of 92.9%. DIPSI classified 15% as screen-positive and showed a sensitivity of 75.0% and specificity of 96.4%. Overall diagnostic accuracy was 91.0% for HbA1c and 93.0% for DIPSI. Agreement between the two screening methods was substantial (κ = 0.68, p < 0.001).

Conclusion: In this study population, both first-trimester HbA1c and DIPSI showed useful diagnostic performance compared with OGTT. HbA1c detected a larger proportion of OGTT-positive cases, while DIPSI showed greater specificity and slightly higher overall accuracy. HbA1c may therefore be useful as an early adjunct to glucose-based screening, while DIPSI remains a practical option in routine antenatal services.