Comparison of the 50 g capillary plasma glucose tolerance test with the 75 g venous plasma glucose tolerance test in pregnancy.
OBJECTIVE
To compare the 50 g oral glucose tolerance test with capillary sampling used in the Mercy Hospital for Women, Melbourne with the 75 g test with venous sampling advocated by the Australasian Diabetes in Pregnancy Society.


METHODS
Both the 50 g and 75 g glucose tolerance tests were performed on 60 women. Criteria for diagnosing gestational diabetes were the combination of a 1-hour capillary plasma glucose > or = 9 mmol/l and a 2-hour glucose > or = 7 mmol/l for the 50 g test and a fasting glucose > or = 5.5 mmol/l and/or a 2-hour venous plasma glucose > or = 8.0 mmol/l for the 75 g test.


RESULTS
Twenty-eight of 60 women had gestational diabetes diagnosed with the 50 g test; 24 of these, and an additional 5 had gestational diabetes diagnosed on the 75 g test. Twenty-seven women had normal results on both tests. The kappa statistic was 0.70. The 1-hour glucose value was similar for both tests, but the 2-hour value was significantly higher for the 75 g test (mean difference 0.65 mmol/l, 95% confidence limits 0.24-1.01 mmol/l, p = 0.003). The area under the curve was similar for the 2 tests.


CONCLUSIONS
The 2 tests diagnose similar women as having gestational diabetes. The combination of a 75 g load and venous sampling gives similar 1-hour but higher 2-hour values than a 50 g load and capillary sampling.
Henry
O A
OA
Department of Obstetrics and Gynaecology, University of Melbourne, Australia.
Shelley-Jones
D C
DC
Oats
J N
JN
Wein
P
P
Beischer
N A
NA
D016640:Diabetes, Gestational / Q000175:diagnosis*; D005260:Female; D005951:Glucose Tolerance Test / Q000379:methods*; D006801:Humans; D011247:Pregnancy