Gestational Diabetes mellitus (GDM) is carbohydrate intolerance that begins or is first recognized during pregnancy. It is associated with increased maternal, fetal and neonatal risks. The prevalence of it is increasing in the U.S. probably due to the increasing rates of overweight and obesity. Testing for GDM may be about to be going through some changes.
The American College and Obstetricians and Gynecologists recommends a two step test, with a screening test being given between 24-28 weeks of pregnancy. If the test is not passed then a 3 hour glucose tolerance test is done to diagnose GDM. If the first and second tests are both positive, then the person has gestational diabetes mellitus, and the pregnancy is managed differently to minimize the additional risk.
In 2013 the American Diabetes Association decided that new guidelines for diabetes are to be promoted. The new standards of care are intended to provide clinicians and patients with the components of diabetes care, treatment goals, and tools to evaluate quality of care. Targets that are desirable for patients are provided.
Diabetes will now be classified as Type 1 where there may be absolute insulin deficiency, Type 2, a progressive lack of insulin secretion on the background of insulin resistance, and Gestational diabetes mellitus, diabetes diagnosed during pregnancy that is not clearly overt.
The diagnosis of diabetes used to be based on glucose measurement, either fasting or the 2 hour value during a glucose tolerance test. Recently an expert international panel has recommended that diabetes can also be diagnosed by a different test called hemoglobin A1C. The A1C test has advantages, including greater convenience, since fasting is not required, and greater analytical testing stability. The older established criteria of fasting blood glucose and 2 hour oral glucose test still remain valid.
These new criteria are: a A1C test over 6.5, or a fasting glucose over 126, or a 2 hour plasma glucose over 200 during an oral glucose tolerance test using 75 gm of glucose.
To accommodate this change, we will be starting to check the hemoglobin A1C level during the initial obstetric evaluation. I expect this will yield better diagnosis of gestational diabetes, with the benefit of better control. This should result in a decreased risk of having babies that are too large, lower chance of having a cesarean, less risk of having diabetes in the future and fewer problems with babies having breathing problems, low glucose levels, and jaundice.
Reference: doi: 10.2337/dc13-S011
Diabetes Care January 2013 vol. 36 no. Supplement 1 S11-S66