Fredrick L. Kiechle, MD, PhD
I read your June 2010 article, “Cola, confection, and confusion: OGTT alternatives for gestational diabetes,” by Kevin Foley, PhD, and Shirley Welch, PhD. Do you have any information that pertains to the two-hour glucose tolerance test after ingestion of a 75-g glucose beverage (since this is the new World Health Organization recommendation), and do you know whether there have been studies on an alternative to the 75-g beverage? Several clinicians in our workplace feel there should be, and is, an alternative and are willing to recommend alternatives that are not standardized. It would be nice to have documentation for or against such practices.
A. Whether the laboratory has alternatives for the glucose beverage used in the oral glucose tolerance test (OGTT) is a relatively common question. Each laboratory must define its specific policy regarding possible substitutions. In our laboratory system we do not allow any substitutions for any of the oral challenges (50 g, 75 g, or 100 g). This decision was made by our chemistry director in consultation with our endocrinology department. However, some medical systems do offer alternatives. A jelly bean alternative was proposed in earlier studies.1,2 The original study substituted jelly beans for the 50-g challenge but not for the 75-g challenge. We reviewed this jelly bean method in CAP TODAY.3 Some clinics provide extensive menus of possible foods and drinks that they allow as substitutions. Examples of substitutions used by one clinic for the 50-g challenge (which could be adjusted for the 75- or 100-g challenges) are as follows:
||Nu Grape Soda
||Sunkist Orange Soda
||Ocean Spray Cranberry Juice Cocktail
||Welch’s Red Grape Juice
||Sunsweet Prune Juice
The laboratory that offers the alternatives above also issues the following caveat: “These alternatives should be used in exceptional cases only, and there are no peer-reviewed references that support these substitutions.” Interestingly, the U.S. Department of Health and Human Services Indian Health Service provides a document that outlines several breakfast-load options. This document cites studies that investigated the food-based alternatives, though the studies were small and often suggest lower cutoff concentrations to increase sensitivity.
Polycose appears to be the best-studied alternative to the glucose drink. Polycose is a glucose polymer that can be purchased as a powder (distributed by Abbott Nutrition). It has been used primarily in infant formulas and as a nutritional supplement, but some have used it as a substitute for glucose challenge testing. Polycose has only 20 percent of the osmotic load of the equivalent mass of anhydrous glucose and thus is better tolerated orally. One study showed that polycose gives rise to plasma glucose concentrations that are very similar to regular glucose and may have less variability.4-6
Most labs probably do not want to prepare a glucose alternative by weighing out powder and preparing the drink on demand. In our system, when a patient cannot tolerate the OGTT, clinicians are reminded there are other options: measure a fasting plasma glucose using the normal ≥126 mg/dL cutoff or a casual plasma glucose with the ≥200 mg/dL cutoff. Both tests are diagnostic when confirmed with repeat testing on a different day. Likewise, a hemoglobin A1c measurement using the
≥6.5 percent cutoff can be used to diagnose diabetes (again, this too must be confirmed with a repeated test on another day). However, it is important to note there is not 100 percent concordance across all tests. The oral glucose tolerance test is more sensitive than routine fasting glucose, random glucose, or an A1c measurement. This has been shown in multiple studies. BMI and other patient characteristics appear to have a big impact on the sensitivity each of these assays has at picking up diabetes in the undiagnosed patient.7
We advise clinicians that there are no well-validated alternatives for any of the OGTTs. It’s also helpful to remind patients that during the test they have up to five minutes to drink the beverage. Drinking it slowly, cold, and perhaps with a straw should help with tolerance. The glucose beverage could also be diluted into a lower concentration using water, as long as the entire volume is still consumed within five minutes.
1. Boyd KL, Ross EK, Sherman SJ. Jelly beans as an alternative to a cola beverage containing fifty grams of glucose. Am J Obstet Gynecol. 1995;173:1889–1892.
2. Lamar ME, Kuel TJ, Cooney AT, et al. Jelly beans as an alternative to a fifty-gram beverage for gestational diabetes screening. Am J Obstet Gynecol. 1999;181:1154–1157.
3. Foley KF, Welch S. Cola, confection, and confusion: OGTT alternatives for gestational diabetes. CAP TODAY. June 2010, 79–80, 82, 84.
4. Reece EA, Gabrielli S, Abdalla M, et al. Diagnosis of gestational diabetes by use of a glucose polymer. Am J Obstet Gynecol. 1989;161:383–385.
5. Schwartz JG, Phillips WT, Aghebat-Khairy B. Revision of the oral glucose tolerance test: a pilot study. Clin Chem. 1990;36:125–128.
6. De Leacy EA, Cowley DM. Variability of glucose tolerance test in pregnancy diminished by use of a glucose polymer. Clin Chem. 1992;38:1388–1389.
7. Lorenzo C, Haffner SM. Performance characteristics of the new definition of diabetes: The insulin resistance atherosclerosis study. Diabetes Care. 2010;33:335–337.
Kevin F. Foley, PhD, DABCC
Regional Director of Clinical Chemistry and Toxicology
Department of Pathology
Kaiser Permanente NW Laboratories
Q. Is it appropriate in a medical laboratory to reuse tourniquets? Does the CAP have any related requirements?
A. Tourniquets are a potential source of methicillin-resistant Staphylococcus aureus (MRSA), with up to 25 percent of tourniquets contaminated through reuse or lack of hand hygiene on the part of the phlebotomist.
To prevent contamination, any common-use items such as tourniquets and blood-pressure cuffs should be disinfected before and/or after use on a patient. A single-use tourniquet is a relatively inexpensive way to ensure patient safety and compliance with the Occupational Safety and Health Administration’s bloodborne pathogens standard 1910.1030(d)(1), which states: “Universal precautions shall be observed to prevent contact with blood or other potentially infectious materials.”
Common sense dictates the use of good hygiene practices to prevent cross-contamination of patients. Given the potential for contamination of the tourniquet with microscopic blood or other skin contaminants, a reusable tourniquet would require decontamination or disinfection before and/or after every use. It would be acceptable to allow reuse if a policy is in place requiring disinfection before and/or after each use (wipe with a Sani-Wipe or similar product) and if this practice is observed during inspection. That said, it is always preferable to use single-patient-use-only items.
Points to remember: 1) Universal precautions should always be observed because contaminants such as MRSA are not visible to the naked eye;
2) Visibly contaminated patient care items should be discarded or undergo a robust decontamination/disinfection process; and 3) Single-use tourniquets are available and inexpensive, and they eliminate cross-contamination when used as directed and discarded after use.
1. BD. BD Vacutainer Stretch Latex-Free Tourniquet. www.bd.com/vacutainer/mailer/stretch/.
2. Kane L, Lucas C, Krischock L. Phlebotomy tourniquets—vectors for bacterial pathogens. Arch Dis Child. 2011;96(suppl 1):A1–A100. doi:10.1136/adc.2011.212563.105.
3. Kiechle FL, ed. So You’re Going to Collect a Blood Specimen: An Introduction to Phlebotomy. 13th ed. Northfield, Ill.: College of American Pathologists; 2010.
4. Occupational Safety and Health Administration. Bloodborne pathogens. www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=standards&p_id=10051. Accessed April 3, 2012.
5. World Health Organization. WHO guidelines on drawing blood: best practices in phlebotomy. whqlibdoc.who.int/publications/2010/9789241599221_eng.pdf. Accessed April 3, 2012.
Eileen Esposito, RN, MPA, DNP, CPHQ
Principal and Executive Consultant
Ambulatory Expert Solutions
Member, CAP Point-of-Care Testing Committee
Bruce Jones, MD
Department of Pathology and Laboratory Medicine
Henry Ford Hospital
West Bloomfield, Mich.
Member, CAP Point-of-Care Testing Committee
Dr. Kiechle is medical director of clinical pathology, Memorial Healthcare, Hollywood, Fla.