By Lorraine L. Janeczko
NEW YORK (Reuters Health) Aug 02 - A diagnosis of gestational diabetes mellitus (GDM) can sometimes be made just on the basis of a glucose challenge test (GCT), new research suggests.
Pregnant women who have 50-g GCT results higher than 200 mg/dL are most likely to need insulin for GDM, the researchers say.
"Clinicians can use these test results to diagnose the women with GDM without putting them through a three-hour oral glucose tolerance test (OGTT)," they wrote in a paper online July 1st in the American Journal of Obstetrics and Gynecology.
"In fact, we found that women with a GCT >200 mg/dl had an even higher rate of requiring insulin treatment than women diagnosed with GDM by a 100-g three-hour OGTT," said lead author Dr. Teresa Hillier, endocrinologist at the Kaiser Permanente Center for Health Research in Portland, Oregon and Honolulu, Hawaii, in an email to Reuters Health.
To analyze the results of screening for GDM and the risk for needing insulin treatment, Dr. Hillier and her group looked at data on 64,687 pregnant women with no preexisting diabetes who were screened for GDM over 16 years in two regions of a large US health plan.
The women were at least 18 years old and of various ethnicities. They were all members of the health plan throughout their pregnancy, and they delivered live singletons.
All the participants had a 50-g, one-hour GCT. The 11,243 women (17.4%) with a reading of >140 mg/dL then took a second screening test, a100-g, three-hour OGTT.
Of that group, 595 (0.9% of the total cohort) had a GCT >200 mg/dL.
The researchers found that 2% of all the pregnant women needed insulin, ranging from 0.1% of those with normal GCT to 49.9% of those with GCT >200 mg/dL (p<0.0001). Women with GCT >200 mg/dL had a significantly higher rate of insulin treatment than women with GDM (odds ratio, 3.7; 95% confidence interval, 3.1 to 4.4).
Women who were diagnosed at 16 weeks gestation, were obese or in high-risk racial and ethnic groups, including blacks, Chinese, Filipinos, Hawaiians and Japanese, needed insulin treatment at much higher rates than low-risk participants (p<0.0001).
Dr. Didac Mauricio, chief physician of the Department of Endocrinology & Nutrition of the Hospital Universitari Germans Trias i Pujol in Badalona, Spain, told Reuters Health in an email that these findings add important information and may change clinical practice.
"At our pregnancy clinic, we will discuss these results and will most probably consider 50-g GCT as diagnostic of GDM with no further diagnostic workup," he said. Dr. Mauricio was not involved in the study.
Co-author Dr. Keith Ogasawara, chief perinatologist in the Department of Obstetrics and Gynecology of Kaiser Permanente Hawaii in Honolulu, added in an email to Reuters Health, "High-risk women screened and diagnosed with GDM during the first trimester (by 16 weeks gestation) are much more likely to require insulin than women diagnosed with GDM between 24 and 28 weeks gestation. Early screening for these women may be beneficial."
Dr. Vincent Wong, from the Diabetes and Endocrine Service at the University of New South Wales in Sydney, Australia, pointed out to Reuters Health, also by email, that many countries, including his, use the 75-g OGTT to screen for and diagnose GDM. "Following the HAPO (Hyperglycemia and Adverse Pregnancy Outcome) study, many countries are abandoning the GCT and using 75-g OGTT," said Dr. Wong, who wasn't involved in the Kaiser research. "This limits the significance of this study," he added.
Drs. Hillier and Ogasawara told Reuters Health in a joint email that right now, screening and diagnosis strategies for GDM are controversial clinical issues. The American Congress of Obstetricians and Gynecologists recommends the two-step screening, while the American Diabetes Association recommends changing to a one-step 75-g OGTT with unique criteria for pregnant women.
They added that the National Institutes of Health has recently called for more research about both methods and issued a statement available at https://prevention.nih.gov/cdp/conferences/2013/gdm/files/DraftStatement.pdf.
Dr. Mauricio has received fees and honoraria from Novo Nordisk, Sanofi and Lilly. All other authors and contributors declared no conflict of interest.
Am J Obstet Gynecol 2013.
Reuters Health Information © 2013