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Keywords:

  • 1 hour 50 g glucose loading test;
  • glucose tolerance test;
  • gestational diabetes mellitus;
  • diabetes in pregnancy

Abstract

A prospective study for detecting gestational diabetes mellitus was undertaken to evaluate the use of one hour plasma glucose level after 50 g glucose loading test (1-hr GLT) as compared to the traditional 3-hours 100 g oral glucose tolerance test (3-hr OGTT) in 396 high risk cases. Each patient, had 1-hr GLT and 3-hr OGTT performed in a separate week. Forty-two cases (10.6%) who had abnormal 3-hr OGTT were classified as gestational diabetes (GDM). One hundred and sixty cases (40.4%) had an abnormal 1-hr GLT (plasma glucose level ≥140 mg/dl). Thirty-six of these 160 cases (22.5%) had an abnormal 3-hr OGTT. In 236 women (59.6%) that had normal 1-hr GLT (plasma glucose level <140 mg/dl) only 6 cases (2.5%) had an abnormal 3-hr OGTT. If 1-hr plasma glucose level ≥150 mg/dl was used as the cutoff point, 110 cases (27.8%) were found to have abnormal 1-hr GLT, and 35 of these 110 cases (31.8%) had an abnormal 3-hr OGTT. Seven of 286 women (2.4%) that had normal 1-hr GLT (plasma glucose level <150 mg/dl) had an abnormal 3-hr OGTT. The sensitivity and specificity of the 1-hr GLT when abnormal 3-hr OGTT was used as gold standard for detecting GDM were 85.7% and 65% respectively (BS ≥140 mg/dl). Whereas the sensitivity and specificity were 83.3% and 78.8% respectively when plasma glucose level >150 mg/dl was used as the cut point. From this study in oriental pregnant women it can be concluded that 1-hr GLT is a valuable screening test for GDM.