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AACE: A1c Is a Promising Diagnostic Tool in Gestational Diabetes

May 2, 2006

Fasting blood glucose and HbA1c testing can be a useful screening tool for gestational diabetes. c Control in Diabetes Showed a Significant Improvement When Compared to Standard Therapy. The diagnosis of gestational diabetes mellitus (GDM) is almost always made with the 100-g oral glucose tolerance test (OGTT), which is given to pregnant women who test positive on the 50-g random glucose test. Because of the inconvenience of the OGTT, a potential diagnostic role for glycosylated hemoglobin Ale (HbAlc) in type 2 diabetes and GDM has been suggested, but few studies have been published. The diabetes community has not yet accepted HbAlc as a diagnostic or screening tool in diabetes. This study evaluates the diagnostic validity of HbAlc in GDM, with possible broader application in type 2 diabetes.
All OGTT tests that were conducted in our central laboratory between January 2001 and April 2002 were reviewed. Tests that were accompanied by HbAlc testing performed concomitantly or close to the OGTT were analyzed. Men and nonpregnant women were excluded. The diagnosis of GDM was based on the results of the OGTT, according to the most recent guidelines. HbAlc was then correlated with OGTT.

All of the 171 patients included in the study had a confirmed diagnosis of GDM. These patients were all Saudis, with the exception of 3 Philippino patients and 1 Yemeni patient. Their mean age (years), weight (kg), gestational age (weeks), and time between OGTT and HbAlc measurement (days) were (mean±SD) 32.5±6.1, 81.2±16, 31±4.6, 10.68±10.4, respectively. The HbAlc for these patients was 6.8%±1 and ranged between 5 and 11%. The laboratory reference range (using a Hitashi analyzer utilizing immunoassay technique) for HbAlc is 4.8 to 6%. The percentage of patents with HbAlc values above the reference range of 6% was 81.3%. This increased to 88.9% when the cut-off was lowered to an HbAlc of 5.7%.


This pilot study suggests that HbAlc may be a reasonably sensitive measure of GDM when measured at approximately the same time that OGTT tests are conducted.

This study suggests that further research employing a prospective design with serial measures of FPG and HbAlc levels-for example, at 28, 32, and 36 weeks may be warranted to determine if HbAlc can be a useful screening tool for GDM.

Presented at the AACE Meeting in Chicago on April 27, 2006. Abstract #113 – Saleh A. Aldasougi, MD, FACE, David Solomon, PhD, Samia Bokhari, MD, Murthaza Khan, MD, and Muneera Shareef MD

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