The Relationship Between Tuberculosis and Diabetes

As of this writing, diabetes mellitus remains a major global health threat. The International Diabetes Federation (IDF) estimates that one in 11 — or a little over nine percent — of the world's population is affected by this disease. Moreover, that number is expected to go up to 10 percent by 2040.

Of the world's adult diabetics, 37 percent are located in the Western Pacific region — composed of 37 countries including Japan, China, and Australia. Meanwhile, one in eight adults in North America and the Caribbean are diabetic; Europe has the highest number of children with type one diabetes, and two-thirds of Africa's diabetics remain undiagnosed.

These are worrisome statistics, but not just because they show how widespread the disease is. Recent studies suggest that diabetes might be linked to a rarer, but arguably deadlier, condition: tuberculosis.

How Diabetes May Increase Tuberculosis Risk

In Chennai, India, researchers studied 209 patients with pulmonary tuberculosis. Of these, 54.1 percent had diabetes, while 21 percent were at risk of developing the same. This is a significant jump from previous estimates, which estimated that 25 percent of tuberculosis patients also suffered from diabetes.

Granted the aforementioned study is still in the preliminary stage. There's a possibility the relationship between tuberculosis and diabetes is correlative but not causative. However, a study by Dr. Bianca I. Restrepo of the University of Texas' Health Science Center suggests it may be the latter.

In a paper presented to the 2013 World Diabetes Congress, Restrepo expanded on studies which found a positive relationship between the two. Since those studies based their data on patients who already had full-blown tuberculosis, they don't answer one question: "If a patient only had latent tuberculosis before, and became pre-diabetic later, would the latter necessarily aggravate the former?"

Based on their findings, the answer is "yes." After analyzing patients from the Texas-Mexico border, they found that diabetes — specifically, type two diabetes — lowered the body's immune response against Mycobacterium tuberculosis (MTB). However, as Restrepo cautions, the efficiency of the response given in the scenario above remains unclear, so further studies on the subject are necessary.

What Has Been Done

Since the relationship between diabetes and tuberculosis has been established, two-prong programs have been set up around the world. For example, the "Directly Observed Treatment, Short-course" (DOTS) program was implemented in Angola, where 474 per 100,000 individuals develop tuberculosis.

Financed by the World Diabetes Foundation, the DOTS program aims not only to educate patients on tuberculosis, but also to ensure that they take the right drugs in the prescribed manner. The DOTS also monitors patients until the end of their treatment.

Likewise, during the 2013 World Diabetes Congress, Dr. Richard Brostrom mentioned similar initiatives implemented in the Pacific region. They're all based on a set of "standards for management of tuberculosis and diabetes," which Brostrom and his team have executed with a great degree of success. 

In addition to these large-scale programs, the medical realm holds promising developments. In 2015, researchers proposed a five-year study to analyze whether bacilli Calmette-Guerin (BCG) — the standard vaccine for tuberculosis — may also be used to treat type one diabetes.

Essentially, BCG stimulates the production of tumor necrosis factor (TNF) in the body. The TNF, in turn, reduces the diabetic immune system's tendency to attack insulin-producing beta cells, while simultaneously encouraging the production of "good" immune system cells.

What Still Needs to Be Done              

The scientific community still has a long way to go. Some have doubts regarding the BCG vaccine. As Dr. Joel Zonszein, director of Montefiore Medical Center's clinical diabetes center, points out, the idea that selective immunosuppression works against diabetes is up for debate. It's a step in the right direction, but it's not yet a cure by any means.

Also, there have been difficulties with the implementation of certain TB-DM (tuberculosis-diabetes mellitus) programs. Dr. Brostrom mentioned several plans, like the profiling of DM patients according to their TB risk and TB screening guidance, which are still works-in-progress. The sooner these plans are refined and implemented, the more patients will be treated, and the more lives can be saved.     

Takeaways

It's important to stress that diabetes does not directly cause tuberculosis. Rather, the former is a contributing factor to the latter — but a significant one.

Considering the prevalence of diabetes, and the global mobility of the human race in general, it's safe to assume tuberculosis may find its way back to developed countries once again. When this happens, there's no guarantee everyone can fight against two potentially-fatal diseases at the same time.

Luckily, humanity still has hope. If the scientific community is willing to dig deeper into the TB-DM relationship and to implement more initiatives to combat one or the other, the worst-case scenario may not happen after all. As Michel Sidibe, UNAIDS executive director, once quipped: "When a virus and a bacteria can work so well together — why can't we?"

Megan Ray Nichols enjoys writing about various topics in health. Now that you’ve learned a bit about tuberculosis, you might like to learn more about mental health.