I recently got a phone call from a colleague asking me what I knew about jelly beans and their use
in screening for gestational diabetes mellitus (GDM). Other than being only vaguely familiar with the notion, I have to admit I didn’t know much.
Screening for GDM is fairly straightforward and is performed between 24 and 28 weeks of gestation. The non-fasting pregnant patient drinks 150 milliliters (about 5 ounces) of a solution containing 50 grams of glucose. One hour later a blood sample is collected and blood glucose measured. If the result is greater than or equal to 140 mg/dL the screening test is considered positive and a formal oral glucose tolerance test (OGTT) is performed. Women with a positive OGTT test are diagnosed as having GDM.
So how do jelly beans fit into all of this? Well the glucose solution that has to be consumed is sickly sweet tasting and many women find it difficult to drink. Many complain about side effects and 15 to 20 percent have nausea and vomiting (which requires re-scheduling of the test). Jelly beans offer an attractive solution to delivering a glucose load into the stomachs of moms-to-be. They are easy and fun to eat (candy at the doctor’s office!) and women report fewer unpleasant side effects when eating them compared to the glucose drink. As a bonus, their use in health care delivery systems portrays a “patient friendly” attitude (and who doesn’t want a happy patient?). Sounds like a win-win situation, right? Maybe not.
A study of 136 women compared screening for GDM with the glucose drink and jelly beans. Regardless of the results, all of them also had the diagnostic OGTT performed. The jelly beans they used were Brach's No. 110 Jelly Beans made from sugar, corn syrup, modified cornstarch, and glucose. Based on an analysis performed by Brach, it was determined that 28 jelly beans provided 50 grams of glucose.
Of those 136 women, 5 of them were diagnosed with GDM based on the results of the OGTT. Screening with the glucose drink identified 80 percent (4/5) of those with GDM and screening with jelly beans identified only 2 of them (40 percent). The diagnostic specificity (the percentage of truly negative results) was similar for both tests at approximately 85 percent.
Tests that screen for a disorder like GDM should be able to detect a high percentage of women with the disease. The use of jelly beans failed to detect more than half of the women with GDM. The authors of the paper recognized that limitation and commented that if other studies found low detection rates the use of jelly beans in a GDM screening test would prevent their use for that purpose. I searched the medical literature using the terms “jelly beans” and “jellybeans” and was unable to identify any similar studies.
When it comes to glucose challenge tests to screen for GDM, I’d lock up the jelly beans and refuse any requests to use them or any other substitute for a 50 g glucose solution.