Pregnancy: What is Glucose Tolerance Testing?

Written by Dr. Manuela Vazquez, May 2023 Manuela Vazquez, MD has practiced as an OBGYN for over a decade in and around Orange County, CA for LA County and Kaiser Permanente. Dr. Vazquez specializes in both female reproductive health as well as gynecological health. As the founder of LaMaria – a GYN dryness skincare line, Dr. Vazquez celebrates advances in women’s’ healthcare. Learn more about Kaiser Permanente OBGYN here.

Gestational Diabetes Mellitus (GDM) impacts 5% - 8.5% of pregnant women. It can occur in any pregnancy regardless of diet regimen and overall health. If left undiagnosed and uncontrolled, there are significant neonatal and maternal risks such as preterm birth, fetal anomalies, preeclampsia, macrosomia, and neonatal issues. To prevent complications associated with GDM, obstetricians, midwives, and doulas have a critical role in educating and screening patients.

Screening for gestational diabetes is usually performed between 24-28 weeks of pregnancy in women who have not been previously diagnosed with diabetes. To diagnose a patient, we evaluate blood glucose levels after the pancreas has been stressed by a very specific amount of anhydrous glucose.  To screen for GDM, a patient will need to consume an approved diagnostic glucose beverage, also known as glucola.  This is often provided by a healthcare provider or laboratory; patients are also allowed to purchase FDA Registered OTC glucose beverages.  There are three different concentrations of glucola so it's important to consume the amount your provider prescribes. There are two distinct testing methods; a one-step approach, and the more common two-step approach. During the one-step approach, a 75-gram glucose  beverage is administered. During the two step approach, a 50-gram and  possibly a 100-gram glucose beverage are administered.

There are many brands of glucola around the world, some are premixed liquid and others are powder form, more commonly seen in Eastern Europe. Here in the United States, the validated brands currently available include Cardinal Health, Thermo Fischer, Azer and Fresh Test.

The glucose beverage and why it’s unique: Anhydrous glucose is metabolized differently than sucrose, fructose, maltose or other substances. Test results will vary greatly if there is an attempt to substitute a diagnostic glucose beverage with unvalidated food alternatives (ie. Jelly beans, Juice, etc.). This is due to the distinct metabolization of anhydrous glucose compared to other carbohydrates such as sucrose, fructose or maltose.  In addition, factors such as fat, protein and fiber can also significantly effect how plasma blood glucose rises. Based on this information, following a physician’s protocol for gestational diabetes screening with a validated glucose beverage is essential.

As healthcare professionals, offering consultative support to our patients is crucial; especially for those women who 1) struggle to tolerate traditional glucose beverages, 2) have anxiety about the testing process, 3) suffer from allergies or 4) follow restrictive and non-gmo diets. In years past, there were no equivalent options that were free of additives until The Fresh Test™ became available a few years ago.  With its organic ingredients, high tolerability and laboratory acceptance, it has become an extremely popular option.  Numerous offices are now stocking the product because it’s eligible for reimbursement through HSAs, FSAs and the screening CPT Codes. Many physicians who have offered The Fresh Test have received stellar reviews from patients regarding their experience. The tolerability and ease of the test is a stark difference from years past when GDM Screening was often noted as a dreaded aspect of pregnancy care. As a practicing physician, I believe our patients deserve better than the antiquated testing that we have to offer and I support the development of better alternatives for the women we care for. Our patients are consistently educating themselves and asking for more natural and holistic options and it is our duty to have those options available for them.

Now, more than ever, pregnant women are more aware of environmental pollutants, toxic ingredients and nutrition labels. We, as providers, also need to be aware of the growing evidence linking exposure to certain toxins with health issues. For further information on this, please refer to the Reducing Prenatal Exposure to Toxic Environmental Agents printed in the 2021 ACOG Committee Opinion  article, Number 832. As technology and products improve, it’s important to keep abreast of the growth in our field so we can provide the most up to date information when patients look to us for options.

As a practicing OBGYN, I am not paid by Fresh Test, but fully support advancements like this in womens’ healthcare.

– Manuela Vazquez, OBGYN & Jacqueline Berg, Founder