Tuberculosis Poses Significant Risk in Diabetes Patients

Tuberculosis poses significant risk in diabetes patients
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Experts have long known that having a condition that compromises the immune system, as diabetes does, increases a person's risk of developing tuberculosis. Now a new study has identified how significant that risk can be in diabetes patients, as well as the risk of dying during tuberculosis treatment.

Tuberculosis is a lifetime risk

Tuberculosis is a preventable, curable, and contagious disease caused by bacteria (Mycobacterium tuberculosis) that typically attack the lungs. One third of people have dormant tuberculosis bacteria, which means they are infected but are not yet sick and cannot pass along the disease to others.

According to the World Health Organization (WHO), people infected with the bacteria have a lifetime risk of falling ill with tuberculosis of 10 percent. Investigators at the University of Copenhagen have just reported on their research which shows the risk of tuberculosis breaking out is four times greater if a person also has diabetes.

The study was conducted in Tanzania, which like other African nations as well as other parts of the developing world (e.g., Asia), is no stranger to tuberculosis. However, the prevalence of diabetes, which typically has been a disease seen in the Western world, is growing in both Africa and Asia, and the combination of tuberculosis and diabetes may prove to be deadly.

The diabetes and tuberculosis study
Researchers evaluated 1,250 patients newly diagnosed with tuberculosis and 350 controls without tuberculosis during a period spanning spring 2006 until fall 2009. The goal was to determine the role of diabetes in risk of tuberculosis, treatment results, and survival among the study population.

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All the participants were tested for diabetes and HIV and were followed up on during their tuberculosis treatment as well as after one year. This is what the researchers found:

  • 38% of tuberculosis patients had impaired glucose metabolism (sign of prediabetes) compared with 21% of controls
  • 17% of tuberculosis patients had diabetes compared with 9% of controls
  • The difference in the incidence rate between tuberculosis patients and controls corresponded to an odds-ratio of more than four, indicating a strong relationship between tuberculosis and diabetes
  • Patients with diabetes had a four times higher death rate while undergoing the intensive stage of tuberculosis treatment

The authors expressed concern that a combination of tuberculosis and the increase in diabetes in the African region could result in an increase in the number of people who die from tuberculosis in the future.

According to physician and PhD student Daniel Faurholt-Jepsen, who wrote his doctoral dissertation on the basis of the study, "Our studies show, firstly that diabetes is hastily advancing in developing countries, not just in Asia, but in Africa as well." He pointed out that "Tuberculosis kills more than a million people each year. The figure may be much higher in the future if nothing is done now."

WHO reports that the estimated number of people falling ill with tuberculosis has been declining very slowly, and that the tuberculosis death rate dropped 40% between 1990 and 2010. What impact will the relationship between tuberculosis and the growing number of diabetes cases in developing countries have on this progress?

SOURCES:
University of Copenhagen
World Health Organization

Image: Wikimedia Commons

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