Comparative Study of Fasting Plasma Glucose Concentration and Glucose Challenge Test for Screening Gestational Diabetes Mellitus

Abstract

Background: To compare the sensitivity and specificity of fasting plasma glucose (FPG) with that of standard glucose challenge test (GCT). Materials and methods:Eighty-nine eligible pregnant women underwent GCT between 24th and 28th gestational week, followed by a diagnostic 3 hours 100 gm oral glucose tolerance test within 1 week. Out patient clinic in Father Muller Medical College Hospital, Mangalore. Data was analyzed for significance by chi-square test.Results: Fasting plasma glucose concentration at a threshold value of 90 mg/dl and GCT at recommended standard threshold of 140 mg/dl yielded sensitivities of 66.7% and 100% respectively and specificities of 87.3% and 46.5% respectively. Reducing the threshold value of FPG to 80 mg/dl increased the sensitivity of test to 91.7% with specificity of 54.9% which was comparable to standard GCT, in our study. Conclusion:Measuring FPG concentration using a cut-off of ≥ 80 mg/dl is an easier, tolerable and more cost effective procedure than GCT for detecting more severe cases of GDM, i.e. the diabetes mellitus group. In resource poor settings with population belonging to average risk or high risk category, FPG at a cut-off of 90 mg/dl can be used to screen GDM.

Screening for Gestational Diabetes

“…eFigure 4 in the Supplement shows findings for the OGCT; results from pooled analyses are summarized in eTable 5 in the Supplement. Against Carpenter and Coustan criteria, at a 140-mg/dL cutoff, the pooled sensitivity and specificity (8 studies, n = 6190) were 81.9% (95% CI, 68.3% to 90.4%) and 81.8% (95% CI, 71.2% to 89.1%), respectively. Against the National Diabetes Data Group criteria (6 studies, n = 5375), the 140-mg/dL cutoff had a sensitivity of 85% (95% CI, 72.0% to 92.6%) and specificity of 81.2% (95% CI, 75.9% to 85.6%).…”

“…At a cutoff of 130 mg/dL, findings against Carpenter and Coustan criteria were inconsistent from 3 studies (n = 1034) (eFigure 4 in the Supplement). Sensitivity of the OGCT against IADPSG criteria was low across all cutoffs in 2 good-quality studies (n = 2091; eFigure 4 in the Supplement); at a 140-mg/dL cutoff, specificity in those 2 studies was 81% and 93%.…”

“…Against Carpenter and Coustan criteria, fasting plasma glucose at a cutoff of 85 mg/dL was associated with sensitivity of 88% (95% CI, 84% to 91%) and specificity of 73% (95% CI, 46% to 90%) and at a cutoff of 90 mg/dL with sensitivity of 81% (95% CI, 75% to 85%) and specificity of 82% (95% CI, 61% to 93%) (3 studies, n = 2233) (eTable 5 in the Supplement). Sensitivity was greater than 90%, although specificity was low (<47%), at cutoffs of 80 mg/dL or less (4 studies; n = 6781) . Against IADPSG criteria, at 24 weeks of gestation or later, fasting plasma glucose testing with cutoffs of 80 mg/dL or less was associated with high sensitivity (most estimates >90%) but low specificity (5 studies; n = 52 532) …”

“…Across the KQs reported in this manuscript, a total of 76 studies were included (18 RCTs [different screening strategies, n = 27 196; treatment benefits and harms, n = 4045], 2 nonrandomized controlled intervention studies of treatment [n = 190], and 56 observational studies [screening benefits, n = 4336; screening harms, n = 166 082; diagnostic accuracy, n = 91 260]) (Figure 2). Twenty-three studies were carried over from the prior USPSTF review and 52 new studies were added.…”

“…Against the National Diabetes Data Group criteria (6 studies, n = 5375), the 140-mg/dL cutoff had a sensitivity of 85% (95% CI, 72.0% to 92.6%) and specificity of 81.2% (95% CI, 75.9% to 85.6%). Using a 135-mg/dL cutoff (4 studies, n = 1554) resulted in higher sensitivity (93.3% [95% CI, 23.7% to 99.8%]; reference, Carpenter and Coustan criteria) but lower specificity (78.9% [95% CI, 53.3% to 92.5%]) than the 140-mg/dL cutoff. At a cutoff of 130 mg/dL, findings against Carpenter and Coustan criteria were inconsistent from 3 studies (n = 1034) (eFigure 4 in the Supplement).…”