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Diabetics at risk of TB (and vice versa)

A report notes that TB rates sky-rocketed in the 1990s fuelled by the HIV epidemic, and warns of a similar situation with diabetes-related TB.

Research shows that people with diabetes are up to three times more likely to develop tuberculosis (TB) than those without the illness. 

Gavin Churchyard, founder and head of the nongovernmental TB research organisation the Aurum Institute, says uncontrolled diabetes weakens the immune system, making a person more susceptible to TB, and can also severely compromise the outcome of TB treatment. There is also evidence to suggest that TB itself is a risk factor for developing diabetes. 

The first report detailing the TB-diabetes link, published by the International Union Against Tuberculosis and Lung Disease and the World Diabetes Foundation at the end of 2014, notes that TB “can temporarily increase the level of blood sugar” — a significant risk factor for developing diabetes. However, “more research is needed” to establish a causal link.

Yogan Pillay, the health department’s deputy director general in charge of HIV and TB, says the correlation between TB and diabetes has only received international attention “fairly recently”, with the first report on the co-epidemic published at the World Lung Health conference in Barcelona last year.

The report’s authors note that TB rates “sky-rocketed” in the early 1990s fuelled by the escalating HIV epidemic and warn that a similar situation is emerging with diabetes-related TB. And with 382-million diabetics worldwide in 2013, which is estimated to almost double by 2030, the authors note that this “looming co-epidemic” could have similarly “catastrophic” consequences. 

A 2007 article in the South African Medical Journal estimates that 1.5-million South Africans have been diagnosed with diabetes. But according to the World Health Organisation (WHO), more than half of diabetes cases in developing countries are not diagnosed and a recent study in the Lancet medical journal revealed that about 15% of TB cases globally are due to diabetes. 

Pillay said that this emerging trend called for a “comprehensive approach to patient management”.  A 2014 Lancet literature review estimates that 8.3% (about 70 000) South African TB cases in 2012 were attributable to diabetes.  “The response to TB has to be broader than just the TB programme. We need to consider all of the groups that are at an increased risk of developing TB such as people with diabetes, renal failure or certain cancer patients,” says Churchyard. 

In South Africa, health department statistics reveal that up to 70% of TB patients are also infected with HIV.  But Pillay says the health department is not unprepared: “We [took] the decision three years ago to integrate HIV screening and testing with screening for diabetes and hypertension. Because we know that people with weak immune systems are at higher risk for TB. That’s why people with HIV are also at high risk of developing TB.”

Amy Green was a health reporter at Bhekisisa from 2013 until 2016.

Ina Skosana was a health reporter at Bhekisisa.