12 October 2017

Here's why diabetics have higher TB risk

A Mexican study has found that uncontrolled diabetics are more likely to develop latent TB than the general population.

New Mexican research has shown that people with uncontrolled diabetes are at a higher risk of latent tuberculosis (TB) infection, a dormant form of TB that only progresses to active disease in about 10% of people.

Previous studies have found that diabetics are up to three times more likely to develop active TB disease than the general population, but none has investigated its association with the latent form of the illness.

Undiagnosed diabetes

Presented at the Union World Conference on Lung Health in Mexico this week, the study also showed that undiagnosed diabetics had one of the highest associations with latent TB infection. This is particularly relevant in Africa which has the highest proportion of adults living with undiagnosed diabetes: two thirds of people with the condition do not know they have it, according to the International Diabetes Federation.

“Detecting latent TB is important,” explained one of the study’s researchers from Stanford University, Dr Leonardo Martinez.

“Considering the higher risk of TB disease for diabetic patients, it’s important to look for prevention opportunities,” he told Health-News. Patients can be offered preventative treatment that kills their latent infection before it has a chance to develop into active disease.

Diabetics are at a higher risk for developing TB as a result of a weakened immune system, one that is much weaker when blood sugar levels aren’t controlled.

TB burden in SA

This study, involving 4 000 patients in the United States, found that undiagnosed diabetics, who are likely to have uncontrolled diabetes, have a 12% prevalence of latent TB infection which is about four times the general population of that country.

But latent TB infection rates in South Africa are drastically higher with varying estimates between 60 and 90%, depending on the data source. This is because South Africa has a much higher TB burden and therefore more people are exposed to the bacteria.

But people with healthy immune systems and who aren’t living with HIV or diabetes for example are at a much lower risk of ever experiencing TB symptoms.

Room for improvement

According to Martinez, although this study needs to be replicated in other countries with high TB burdens like South Africa, it suggests counties should routinely test diabetics for latent TB (and vice-versa) and offer them preventative therapy as well as be more active in finding the undiagnosed cases.

The South African Department of Health’s Dr Norbert Njeka, in charge of drug-resistant TB, said that the country has had “challenges” integrating services. These services have been traditionally separated into infectious and noncommunicable diseases but, he said, that distinction is becoming less relevant as more research shows how many of these diseases are connected.

According to Martinez, although “it can be very difficult” to integrate services, “there is a lot of room for improvement and we cannot continue to work in silos: It would help both of we worked together a little bit better”. – Health-e News.

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