RENO, NEV. — Oral glucose challenge test results appear to have different values for patients of different ethnicity, reported Tania Esakoff, M.D.
Specifically, Asians may need to meet a higher threshold cutoff than whites before undergoing a 3-hour fasting glucose tolerance test to determine whether they have gestational diabetes, and African Americans need a lower cutoff, Dr. Esakoff and her colleagues wrote in a poster presented at the annual meeting of the Society for Maternal-Fetal Medicine.
The researchers reviewed the records of 14,565 pregnancies screened for gestational diabetes with the 50-g glucose loading test in ethnically diverse San Francisco. They then computed the sensitivities and false-positive rates based on study results and known results for fasting glucose tolerance testing.
The results show Asians tend to be more sensitive to an oral glucose challenge and therefore need a higher cutoff, said Dr. Esakoff of the University of California, San Francisco.
With the currently recommended cutoff of a serum-glucose level of 140 mg/dL, which is now used for everyone regardless of ethnicity, the test would have a sensitivity of 89% and a false-positive rate of 14% for Asian women.
To reduce the false-positive rate closer to 10%, Asians need to have a cutoff threshold of 145 mg/dL, but then the sensitivity is only 80%.
In African Americans, on the other hand, the test at a cutoff of 140 mg/dL has a sensitivity of 94%, but a false-positive rate of only 6%.
The study suggests if the goal is to have the maximum sensitivity with a near 10% false-positive rate, the threshold cutoff glucose level for African Americans should be 135 mg/dL; for Hispanics and whites, 140 mg/dL; for Asians, 145 mg/dL.
If the goal is to have at least a 95% sensitivity, then the cutoff needs to be 135 mg/dL for African Americans (sensitivity 97%, false-positive rate 9%), and 130 mg/dL for the other ethnic groups.
At the 130 mg/dL cutoff, the false-positive rates are high for those groups (whites 18%, Hispanics 19%, and Asians 24%), but a higher cutoff of 135 mg/dL does not achieve a 95% sensitivity.
The researchers also found an overall prevalence of gestational diabetes in its population of 6%, with a prevalence among whites of 4%, and African Americans of 4%, and Hispanics of 7%, and a prevalence among Asians of 10%.