UT Researchers Find Diabetes and T.B.
Go Hand-in-Hand
in Border Region
HOUSTON – (Sept. 26, 2006) – Patients with diabetes appear to be more at risk for developing active tuberculosis, based on a retrospective study conducted in the Texas-Mexico border area by Blanca Restrepo, Ph.D., assistant professor of epidemiology at The University of Texas School of Public Health’s Brownsville Regional Campus and a group of researchers.
Joseph B. McCormick, M.D.
In addition, tuberculosis patients self-identified as being diabetic generally had a more severe form of tuberculosis that included expectoration of blood, cavities in lung tissue and increased morbidity, as well as a poorer response to drug treatment compared to those without diabetes.
Joseph B. McCormick, M.D., regional dean of the school’s Brownsville campus, is the senior author of an article about the study now available online and due to be published soon in the Cambridge University Press journal, Epidemiology and Infection.
“There is some direct evidence that diabetes lowers the immune system, making diabetics more prone to infection and slower to heal,” said McCormick, who also is the James Steele Professor in the school’s Center for Infectious Diseases. “Our hypothesis is that diabetic people harboring the tuberculosis bacteria in their lungs are no longer able to keep it at bay and it goes from latent to active.”
The study, undertaken by the bi-national consortium Nuevo Santander Tuberculosis Trackers (NSTT), was funded by the National Institute of Allergy and Infectious Disease and the NIH National Center for Minority Health Disparities.
Other authors of the article include representatives from the Secretaria de Salud de Tamaulipas, Ciudad Victoria, Mexico, and the Texas Department of State and Health Services (Region 11, Harlingen).
According to State of Texas figures, the poverty-stricken Texas-Mexico border region has one of the highest incidences of tuberculosis in the United States, as well as obesity-related type 2 diabetes. Texan tuberculosis-diabetes cases were more likely to be Hispanics of Mexican origin.
Two large databases of tuberculosis patients from South Texas (from 1996 to 2002) and Northeastern Mexico (1998-2003) were analyzed. Only patients over the age of 20 were included to focus on type 2 diabetes, which McCormick said has become an epidemic in the U.S.
Self-reported diabetes was by far the most common co-morbidity in the database, with a prevalence of 17.8 percent in the 3,506 patients in Mexico and 27.8 percent in the 1,543 patients in Texas.
Self-reporting by patients is generally thought to underestimate the true percentage of diabetes by 23 to 30 percent, the authors wrote in the study article, since many people are unaware they have the disease.
As a result of the preliminary findings from the diabetes-tuberculosis analysis, NSTT has now embarked on a prospective study. So far, McCormick said, of the approximately 75 patients they have seen, 40 percent have either diabetes (30 percent) or impaired fasting blood glucose (10 percent).
“This has global implications,” the authors said. “Projections are that by 2010, there will be 220 million people globally with diabetes. As type 2 diabetes continues to grow, it will likely affect countries such as India and China that already have a lot of tuberculosis. The Texas-Mexico border is a microcosm of what will happen worldwide.”
Additional co-authors from the UT School of Public Health are: Susan P. Fisher-Hoch, M.D., professor of epidemiology; Adriana Pérez, Ph.D., assistant professor of biostatistics; and Erin Whitney, who was an M.P.H. candidate at the time of the study and since has earned her degree.
View the on-line version of the upcoming Epidemiology and Infection article, here.
Media Contact: Deborah Mann Lake
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