Glucose Metabolism Disorder Is Associated With Pulmonary Tuberculosis in Individuals With Respiratory Symptoms From Brazil

PLoS One. 2016 Apr 14;11(4):e0153590. doi: 10.1371/journal.pone.0153590. eCollection 2016.

Abstract

Background: Diabetes mellitus (DM) has been associated with increased risk for pulmonary tuberculosis (PTB) in endemic settings but it is unknown whether PTB risk is also increased by pre-DM. Here, we prospectively examined the association between glucose metabolism disorder (GMD) and PTB in patients with respiratory symptoms at a tuberculosis primary care reference center in Brazil.

Methods: Oral glucose tolerance test was performed and levels of fasting plasma glucose and glycohemoglobin (HbA1c) were measured in a cohort of 892 individuals presenting with respiratory symptoms of more than two weeks duration. Patients were also tested for PTB with sputum cultures. Prevalence of pre-DM and DM (based on HbA1c) was estimated and tested for association with incident PTB. Other TB risk factors including smoking history were analyzed.

Results: The majority of the study population (63.1%) exhibited GMD based on HbA1c ≥5.7%. Patients with GMD had higher prevalence of PTB compared to normoglycemic patients. Individuals with DM exhibited increased frequency of TB-related symptoms and detection of acid-fast bacilli in sputum smears. Among patients with previous DM diagnosis, sustained hyperglycemia (HbA1c ≥7.0%) was associated with increased TB prevalence. Smoking history alone was not significantly associated with TB in our study population but the combination of smoking and HbA1c ≥7.0% was associated with 6 times higher odds for PTB.

Conclusions: Sustained hyperglycemia and pre-DM are independently associated with active PTB. This evidence raises the question whether improving glycemic control in diabetic TB patients would reduce the risk of TB transmission and simultaneously reduce the clinical burden of disease. A better understanding of mechanisms underlying these associations, especially those suggesting that pre-DM may be a factor driving susceptibility to TB is warranted.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Blood Glucose / metabolism
  • Brazil / epidemiology
  • Comorbidity
  • Diabetes Mellitus / blood
  • Diabetes Mellitus / epidemiology*
  • Fasting / blood
  • Female
  • Glucose Metabolism Disorders / blood
  • Glucose Metabolism Disorders / epidemiology*
  • Glucose Tolerance Test
  • Glycated Hemoglobin A / metabolism
  • Humans
  • Incidence
  • Logistic Models
  • Male
  • Middle Aged
  • Prediabetic State / blood
  • Prediabetic State / epidemiology*
  • Prevalence
  • Prospective Studies
  • Respiratory Distress Syndrome, Adult / blood
  • Respiratory Distress Syndrome, Adult / epidemiology*
  • Risk Factors
  • Smoking / blood
  • Smoking / epidemiology
  • Sputum / microbiology
  • Tuberculosis, Pulmonary / blood
  • Tuberculosis, Pulmonary / epidemiology*
  • Tuberculosis, Pulmonary / microbiology

Substances

  • Blood Glucose
  • Glycated Hemoglobin A

Grant support

This study was supported by Conselho Nacional de Pesquisa e Tecnologia – CNPq (grant number: 559276/2009-5), Brazil and Fundação José Silveira (intramural program), Brazil. The authors JLA-J and LG-S received research fellowships from Fundação de Amparo à Pesquisa do Estado da Bahia. HK’s participation was supported by the Government of India’s Department of Biotechnology, the Indian Council of Medical Research, the United States National Institutes of Health distributed by CRDF Global through grant #USB1-31149-XX-13.