The impact of Diabetes Mellitus on epidemiological, clinical, radiological features of tuberculosis. Seven years experience in a Mexican teaching hospital

Background: studies from Asia revealed a threefold increase in the risk of active tuberculosis (TB) for patients with diabetes mellitus (DM). Given the increasing incidence of metabolic syndrome and DM in developing countries with a high incidence of TB, there may be a convergence of the two diseases resulting in increased morbidity and mortality with a high impact for global health. The aim of this study was to evaluate the contribution of type 2 DM to TB rates in Mexican population. A comparison with TB/HIV coinfection was also done. Materials and Methods: we performed a retrospective study in the Civil Hospital “Fray Antonio Alcalde”, Guadalajara, Mexico. All TB patients hospitalized between 2005-2011 were studied. Demographic data, clinical and radiological findings and sputum microscopy were assessed in TB patients with and without DM and in a TB/HIV coinfected group. The data underwent statistical analysis. We used Pearson’s x2 test to compare the characteristics of the three groups, a P value of <0.05 was considered statistically significant. For continuous variables the non-parametric analysis of MannWhitney U test was used. Results: a total of 1225 patients with TB were analysed and DM type 2 was diagnosed in 16.8% of TB patients, whereas HIV infection was observed in 9.1%. Smoking/alcohol/drugs use and a history of prison were more common in TB/HIV patients (p≤0.001), while no significant differences were found between TB/DM and non-DM patients. TB/DM patients showed more symptoms like expectoration and haemoptysis, (p<0.05); cavitations were more often found in TB/DM (p<0.05). Also fibronodular forms were more common in TB/DM (p<0.05). By contrast in the TB/HIV group, the constitutional symptoms and miliar lesions were prevalent. Regarding sputum microscopy no differences were detected at the time of diagnosis, while at 2 months of follow-up TB/DM and TB/HIV patients were still positive (17.1% and 17.2,% versus 12.7% of only TB). At the end of treatment TB/HIV showed the higher % of positive sputum. Discussion: although HIV is considered to be the most important risk factor for TB development, we cannot ignore DM, which showed a significantly higher prevalence in active TB patients compared to HIV+ people. A global strategy to improve prevention, early detection and treatment of concomitant DM and TB should be implemented.