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The dual threat of diabetes and tuberculosis

Monday, March 24, 2014 was World TB Day. CNN released Diabetes and TB: A growing threat on March 24, 2014. Dr. Susan Fisher-Hoch, MD is a professor at the University of Texas Houston School of Public Health at Brownsville, TX. Fisher-Hoch wrote this feature article on the increase of tuberculosis (TB) in all 50 states in the US, and around the world, and the link between TB and diabetes.

The race is on to stop the spread of diabetes
Photo by Jerry Markland/Getty Images

TB increased dramatically in the 1980’s with the growth of AIDS/HIV. TB is now growing fastest among the population of diabetes patients due to the weakened immune system caused by diabetes. Many of the medicines used to treat TB do not produce the expected response when the TB patient is also diabetic. The global increase in obesity has increased diabetes dramatically, and exposes more people to TB.

Fisher-Hoch recommends that all physicians treating diabetes patients check them for the presence of TB. This has not been the common practice in the US. TB is not generally considered a major problem in the US despite 9,600 new cases in 2013. TB has been seen mainly in states on the Mexican border and in the Pacific Northwest. Other areas with increased incidence of TB are found where the overall health of the population is compromised due to poor health care such as in Appalachia and in homeless populations of major cities.

TB can be dormant for 10 years or longer before symptoms appear. In the Pacific Northwest, it is estimated that 20 to 30% of new active cases of TB are in patients with diabetes. The Mayo Clinic offers guidance as to the symptoms of active TB. If the TB occurs outside of the lungs, standard symptoms such as coughing up blood may not be present. Latent TB is not contagious, but it can become active and then highly contagious.

A major issue in treating TB in diabetic patients is that their compromised immune system extends the period needed to overcome the TB bacteria. New strains of drug resistant TB bacteria have been occurring as TB bacteria have mutated when the drugs have not totally eliminated the existing TB bacteria. Given the spread of TB among individuals with compromised immune systems, the relationship of TB and diabetic patients creates a perfect storm.

Fisher-Hoch summarizes the need for a new approach for finding and curing TB.

“We must educate health care providers, patients and communities. All TB patients should be screened for diabetes. Diabetes caregivers and their patients need to be aware of the risk of TB, and patients born in or traveling to neighborhoods or countries where TB is common should be screened. If TB is found, these patients need treatment, along with the support they need to get through the many months of daily medication.”

Fisher-Hoch goes on to describe the necessary role that government must hold in slowing the growth of TB.

"We also need strong investment in research and development of TB vaccines, rapid and inexpensive diagnostic methods for both TB and diabetes, and fast-acting, easy-to-take TB medication. Research largely depends on government funding since the pharmaceutical industry shows little interest in TB. Congress has not made TB a priority despite the increasing risk to the public at large."

The global epidemic of obesity, which is increasing most rapidly in China and India, has led to much higher incidence of TB in these countries. Mexico and Caribbean countries have some of the highest levels of diabetes, and some of the poorest health care. This combination of TB and diabetes assures that TB will continue to spill over to countries bordering these nations, and to travelers that have been in these areas.

The release of a study on March 4, 2014 in the journal Cell Metabolism has defined the mechanism that links obesity to the metabolic syndrome known as insulin resistance. The link has now been defined through the integration of two studies at Beth Israel Deaconess Medical Center by a team led by Barbara Kahn, MD and a team lead by Pedro M. Moraes-Vieira, PhD. The studies determined the specific interactions that triggered the auto-immune system to activate an immune response that ultimately ends in obesity causing type II diabetes.

At this point, the US pharmaceutical companies do not consider the development of an effective TB vaccine to be economically attractive. Funding for research on TB prevention and treatment has not been a high priority to date. As the populations of the world become increasingly obese, the incidence of diabetes and TB will grow to epidemic proportions.

It is important that those in the medical profession respond to this new information linking obesity, diabetes and TB by encouraging weight loss, cross screening of diabetic and TB patients, and the development of new treatments and vaccines to slow the spread of TB.