The Looming Co-epidemic of TB-Diabetes: A Call to Action
The recently released report from the International Union Against Tuberculosis and Lung diseases (IUALTD) and the World Diabetes Foundation (WDF) titled “The Looming Co-epidemic of TB-Diabetes: A Call to Action” draws attention to a major public health problem in the developing world that is particularly relevant to India. The report attracted wide media attention because of its coverage by Reuters and other major media channels.
India has an estimated 65 million people with diabetes (17% of the global diabetes burden), half of them undiagnosed and even among those who are diagnosed a big majority is either untreated or poorly controlled. India also has an estimated 2.3million cases of TB annually (25% of the global burden); approximately 30% remain undetected and untreated. The report brings to attention the fact that diabetes on an average increases the risk of TB 2 to 3 fold and that people with TB have high rates of diabetes often undiagnosed. It also points out that the association of TB and DM increases risk of poor TB outcomes including delayed sputum conversion after initiating TB treatment; meaning that these patients continue to remain infective and capable of spreading infection for a longer duration; they have a 4 to 5 times higher risk of death while on TB treatment; and have increased rates of TB relapse and reinfection. While not well documented they may as a corollary to the above also have a high risk of getting multi drug resistance tuberculosis.
It is important to note that the excess risk of TB amongst people with diabetes in primarily related poor diabetes control and high blood sugar. It has been shown that in the presence of high blood sugar immune cells that are responsible for ingesting and killing TB bacilli while retaining their ability to ingest TB bacilli have lowered ability to kill them thus providing a safe harbor to TB bacilli, prolonging the infection, increasing risk of relapse and treatment failure. Moreover presence of diabetes, affects actions and toxicity of some common anti TB drugs. Also interactions between TB drugs and diabetes treatment may interfere with both treatments. Ensuring good control of diabetes almost eliminates the excess risk of TB.
In India the rate of TB case identification in people with diabetes is about 8 times higher than in the general population according to recently published studies. Approximately half of the 65 million people with diabetes in India are diagnosed. If these 33 million cases were screened for TB it would yield about 300,000 cases of TB annually which is about 15% of the TB burden in India. Recent studies from India have also shown that one out of every four or five person with TB has co existing diabetes, half of them previously unknown and discovered only through systematic screening of TB patients for diabetes. If all 2.3 million cases of TB were screened for diabetes this would help identify about 150,000 new cases of diabetes who may otherwise remain untreated and develop complications including poor TB outcome.
The report calls for enhancing the implementation of the WHO Union Collaborative Framework for TB and diabetes through real action on the ground and making resources available to address the double burden. In India the diabetes pandemic is a much bigger threat to the TB control efforts than presently understood and requires urgent public health attention to systematically deal with the double burden. If we don’t act now to head this off, we’re going to experience a co-epidemic of TB-diabetes that will impact millions and sap public health systems of its scarce resources. The key is to prevent this from happening.
The author is an expert in the field of diabetes care and ex-managing director of the World Diabetes Foundation. He is presently a member of the governing board of WDF and advisor to several professional bodies.