The link between diabetes and tuberculosis (TB) has been known for the past two millennia with Avicenna (780-1027 AD) commenting then that “phthisis” (tuberculosis) frequently complicated diabetes. Death was imminent then within five years ‘upon diagnosis of diabetes and the usual cause of death was tuberculosis. The relative risk of contracting tuberculosis is up to five or seven times higher in diabetics and this risk has been. seen in studies done in both developed and developing countries.

The exact nature of the association between diabetes and tuberculosis, up to this date; has not yet been clearly elucidated. Diabetes depresses a person’s immunity en banc and the main killer cell for the Mycobacterium (the tuberculosis organism) is not fully activated in diabetics.  A prospective community-based study in Mexico that did genotyping on the Mycobacterium isolates showed that tuberculosis among diabetics is either a reactivation of a previous infection or a recently transmitted infection.

The symptoms of tuberculosis can mimic that of diabetes.   Loss of weight, loss of appetite and weakness are common to both the diseases.  The other symptoms indicating tuberculosis are cough that is usually prolonged (more than two weeks), fever or feverish sensation, blood streaking of phlegm, and back pains. Several cases of active tuberculosis could not recall any symptoms though and are often discovered upon having a chest X-ray. This happened in four to seven percent of the 9,286 subjects in the National TB Prevalence Survey in 1997. The sputum examination for the tuberculous organism is the test that confirms the diagnosis of pulmonary tuberculosis, however, it turns out to be negative in 50 percent of active TB cases. The doctor, in this case, makes a clinical judgment if tuberculosis is likely to be present, or not.

Many studies have reported that pulmonary tuberculosis presents in a different manner among diabetics. Diabetics have allegedly more cavitary lesions, less sputum positivity and with relative paucity of symptoms and signs. There is a special radiologic patter for “diabetic tuberculosis” consisting of confluent, cavitary, wedge-shaped findings on a chest x-ray, and predominantly being in the lower lung zones.  However, recent prospective surveys have shown that the radiologic pattern for tuberculosis among diabetics are no different from non-diabetics.

Since TB among diabetics can be due to reactivation of a past infection, diabetics are considered among the special populations who should undergo screening for latent or occult tuberculosis infection through targeted tuberculin skin testing. The decision to do the tuberculin test though is considered the decision to treat if the result is positive, hence, if there is no plan for treatment upon proof of latent infection, then the tuberculin test need not be done.

Other preventive measures against tuberculosis ,consist of basic personal hygiene, good diabetes control; and screening the household ,and place of work for active TB Cases. The tubercle bacilli are aerosol borne and transmitted through inhalation of droplets from the cough, sneeze or talking in close proximity with an infected person.  It takes a prolonged period of close contact with an infected person to acquire the disease.

Treatment of tuberculosis among diabetics follows the same principles of tuberculosis management. At least three or four kinds of medications (isoniazid, rifampicin, pyrazinamide, ethambutol and streptomycin) are the usual first-line anti-tuberculous drugs. These medications are now available in fixed-dose combinations to lessen the number of tablets ingested daily so as to improve compliance. Medications are given for at least six months. Compliance to intake of medications, therefore, is the main factor for the proliferation of the TB epidemic. Directly Observed Treatment (DOT) where the patient swallows his or her medicines in front of a medical personnel or representative is the most effective method of treatment to combat the problem of compliance and has been the most effective intervention to decrease TB prevalence. DOT is available nationwide through government and non-government agencies.

Earlier studies mentioned that treatment response to the first-line anti-tuberculous drugs among diabetics are impaired, however, more recent studies show that the cure rate and conversion to sputum negative state among diabetics are similar to non-diabetics. The use of rifampicin may interact other anti-diabetic drugs such as sulphonylureas and biguanides so that the doses of these drugs may need to be increased during rifampicin use. Strict blood glucose control would benefit tuberculosis treatment with the aim of improving the cellular and humoral immunity the diabetic mounts against the infection.

A study in New York City looked into the risk of contracting multi-drug resistant tuberculosis among diabetics and they concluded that a diabetic tuberculosis patient is almost nine times more likely to have MDR-TB than a non-diabetic TB patient. This study was, however, a retrospective one and it was done before DOT was in place in the locality.

New hypotheses are being generated as to the other side of the coin-tuberculosis causing or lessening the chances of acquiring diabetes. Some investigators have found pancreatic islet amyloid deposits as a by-product of systemic tubercular infection thus causing type 2 diabetes. Furthermore, mycobacterial elements have been shown recently to cause “autoimmune” type 1 diabetes in mice but, on the contrary, have also been shown to act as a vaccine to stop the inevitable diabetes that would otherwise materialize.

The Philippines is at the epidemiologic crossroad where two epidemics have converged – infectious diseases such as tuberculosis are still prevalent and chronic diseases such as diabetes are also national concerns. It is heartwarming to note that a lot of effort and coordination are seen from both government and non-government agencies and organizations in combating these two dreadful epidemics of diabetes and tuberculosis.