One-hour glucose tolerance test accurate, convenient for postpartum assessment
The one-hour test identified dysglycemia in 60 of 70 patients who were also diagnosed by their two-hour glucose value, as well as 96 additional patients, a single-center Canadian study found.
A one-hour oral glucose tolerance test (OGTT) may help increase rates of postpartum reclassification following gestational diabetes, results of an observational study suggest.
To compare the ability of one-hour and two-hour OGTT measurements at three months postpartum to predict dysglycemia over the first five years postpartum, researchers had 369 women undergo multisample two-hour 75-g OGTTs at three months, one year, three years, and five years postpartum. Dysglycemia was defined as a composite of intermediate hyperglycemia, prediabetes, and diabetes. All women had a range of glucose tolerance during pregnancy, from normoglycemia to gestational diabetes, and were recruited from a single institution in Canada. Findings were published by Diabetes Care on March 3.
At the three-month test, the one-hour glucose measurement identified 60 of 70 women concurrently who were diagnosed with dysglycemia by two-hour glucose measurement, while diagnosing an additional 96 women. The cumulative incidence of dysglycemia progressively increased over five years of follow-up by tertile of one-hour glucose on the three-month OGTT (P<0.0001). One-hour glucose was the strongest predictor of dysglycemia on regression analyses (change in concordance index [CCI], 16.1%), followed by two-hour glucose (14.9%), non-White ethnicity (6.7%), fasting glucose (5.2%), and body mass index (3.2%). One-hour glucose was also the strongest predictor of dysglycemia in women with gestational diabetes (13.0%), followed by two-hour glucose (12.8%), body mass index (4.2%), and non-White ethnicity (3.1%).
Limitations to the study include a lack of data on lipid levels and metabolic syndrome or any evaluation of the effects of one-hour glucose by ethnic group.
Overall, “regression analyses adjusted for clinical risk factors for diabetes reveal that, on the OGTT at 3 months postpartum, the 1-h glucose value is a stronger predictor of subsequent dysglycemia over the first 5 years after pregnancy than is the 2-h glucose value, both in the full study population and in women with recent [gestational diabetes],” the authors wrote.
A one-hour OGTT might also be a more convenient option than the two-hour test and may increase adherence to the testing recommended for postpartum reclassification following hyperglycemia in pregnancy, they concluded.