WHO 75 gram OGTT-A single step procedure for screening and diagnosis of gestational diabetes mellitus

Abstract

Background: Indian women have an eleven fold increased risk of developing glucose intolerance during pregnancy compared to Caucasian women .Universal screening for GDM is essential in India. This study was undertaken to find out a single step procedure which serves both as a screening and a diagnostic tool.  Methods: This study was carried out in a tertiary care teaching institute in Karnataka. 839 pregnant women with gestational age between 24-28 weeks were subjected to 50 gram OGCT and venous blood was drawn after 1 hour. These patients were requested to come after 72 hours on empty stomach for WHO-75 gram OGTT. Fasting and 2 hour blood samples after 75 gram of glucose were drawn. Results: Amongst the 839 pregnant women who underwent 50 gram OGCT, 136 (16.2%) women had one hour plasma glucose >140 mg/dl. Subsequent 75 gram OGTT revealed that only 43 (31.62%) of screen positive patients were diabetic.93 women who tested positive by 50 gram OGCT were false positive cases (10.58%). Prevalence of GDM in study population was 6.3 % (53/839). Screening OGCT missed 10 (15.87%) of gestational diabetes mellitus cases which were picked up by 75 gram WHO OGTT only. Conclusions: The diagnosis of Gestational Diabetes Mellitus by OGTT based on initial OGCT screening leaves 15.87% undiagnosed. The two step method of screening OGCT and diagnosing GDM with subsequent OGTT is tedious and not economical. Instead a single step WHO 75 gram fasting OGTT with 2 hour PPG ≥ 140 mg/dl is simple and precise.