Fig. 1Correlation of glycosylated hemoglobin (HbA1c) with each value of 100 g oral glucose tolerance test (OGTT) (A, fasting; B, 1-hour; C, 2-hour; and D, 3-hour). r=Pearson's correlation coefficient.
Fig. 2Receiver operating characteristic curve showing the sensitivity and specificity of glycosylated hemoglobin in detecting gestational diabetes mellitus.
Table 1Comparison of women with and without GDM
Variable |
GDM (n=109) |
Non-GDM (n=234) |
P valuea
|
Age, yr |
32.38±3.95 |
30.89±3.68 |
0.001 |
Hemoglobin, g/dL |
11.89±0.74 |
11.80±0.58 |
0.305 |
50 g OGTT 1-hr, mg/dL |
170.34±16.77 |
155.69±12.41 |
<0.001 |
OGTT fasting, mg/dL |
98.30±9.43 |
88.85±6.22 |
<0.001 |
OGTT 1-hr, mg/dL |
193.97±28.26 |
150.53±23.19 |
<0.001 |
OGTT 2-hr, mg/dL |
172.29±31.72 |
133.28±17.91 |
<0.001 |
OGTT 3-hr, mg/dL |
133.09±36.29 |
108.92±19.88 |
<0.001 |
Glycosylated hemoglobin, % |
5.64±0.33 |
5.27±0.21 |
<0.001 |
Table 2Selected threshold values of glycosylated hemoglobin and associated data
Variable |
Value |
Threshold percentage, % |
5.05 |
5.15 |
5.25 |
5.35 |
5.45 |
5.55 |
5.65 |
5.75 |
5.85 |
No. of patients ≥threshold (TP+FP) |
304 |
268 |
234 |
163 |
116 |
78 |
56 |
40 |
28 |
% of patients ≥threshold |
88.6 |
78.1 |
68.2 |
47.5 |
33.8 |
22.7 |
16.3 |
11.7 |
8.2 |
Sensitivity, % |
98.2 |
95.4 |
93.6 |
87.2 |
73.4 |
50.5 |
42.2 |
31.2 |
23.9 |
Specificity, % |
15.8 |
29.9 |
43.6 |
70.9 |
84.6 |
90.2 |
95.7 |
97.4 |
99.1 |
Positive predictive value, % |
35.2 |
38.8 |
43.6 |
58.3 |
69.0 |
70.5 |
82.1 |
85.0 |
92.9 |
Negative predictive value, % |
94.9 |
93.3 |
93.6 |
92.2 |
87.2 |
79.6 |
78.0 |
75.2 |
73.7 |
False positive rate, % |
84.2 |
70.1 |
56.4 |
29.1 |
15.4 |
9.8 |
4.3 |
2.6 |
0.9 |
False negative rate, % |
1.8 |
4.6 |
6.4 |
12.8 |
26.6 |
49.5 |
57.8 |
68.8 |
76.1 |
Positive likelihood ratio |
1.17 |
1.36 |
1.66 |
3.00 |
4.77 |
5.15 |
9.81 |
12.00 |
26.56 |
Negative likelihood ratio |
0.11 |
0.15 |
0.15 |
0.18 |
0.31 |
0.55 |
0.60 |
0.71 |
0.77 |
TN+FN |
39 |
75 |
109 |
180 |
227 |
265 |
287 |
303 |
315 |
Youden index |
0.140 |
0.253 |
0.372 |
0.581 |
0.580 |
0.407 |
0.379 |
0.286 |
0.230 |