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Impact of diabetes mellitus on treatment outcome of newly diagnosed smear-positive pulmonary tuberculosis patients: A case–Control study

1 Department of Respiratory Medicine, Kalinga Institute of Medical Sciences, Bhubaneswar, Odisha, India
2 Department of Respiratory Medicine, SLN Medical College and Hospital, Koraput, Odisha, India

Date of Submission24-Nov-2021
Date of Decision30-Jan-2022
Date of Acceptance04-Feb-2022

Correspondence Address:
Saswat Subhankar,
Department of Respiratory Medicine, Kalinga Institute of Medical Sciences, Bhubaneswar, Odisha
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/mjdrdypu.mjdrdypu_911_21


Background: Tuberculosis (TB) and diabetes mellitus (DM) are major public health problems in developing countries such as India. The link of DM and TB is more prominent in these countries where TB is endemic, and the burden of DM is increasing. Studies regarding the effect of DM on smear conversion and treatment outcome of pulmonary TB (PTB) in India are limited. Aims: The study aimed to compare the conversion and treatment success among new smear-positive PTB patients with and without DM. Materials and Methods: A case–control study was conducted in the department of pulmonary medicine of a tertiary care hospital in eastern India between October 2019 and September 2020. All newly diagnosed smear-positive drug-sensitive PTB patients visiting the outdoor or being admitted were identified, and their initial smear status, history of diabetes, and glycemic status were recorded. All the patients were treated with category I regimen of the Revised National TB Control Program. Sputum smear was followed up at the end of intensive phase and at the end of treatment and compared between diabetic and nondiabetic patients. The software SPSS version 16 was used to analyze all the data. Results: Sixty newly diagnosed smear-positive PTB patients with DM and sixty smear-positive PTB without DM were included in this study. Smear conversion was seen in 24 (40%) out of 60 diabetic TB patients and 55 (91.7%) out of 60 nondiabetic TB patients. Treatment success was seen in 40 (66.7%) out of 60 diabetic TB patients and 56 (93.3%) out of the 60 nondiabetic TB patients. Conclusion: Smear conversion and treatment success rate are lower in diabetic TB patients as compared to nondiabetic TB patients.

Keywords: Diabetes mellitus, treatment outcome, tuberculosis

How to cite this URL:
Rout P, Jagaty SK, Behera D, Subhankar S, Mohapatra SK, Panda G. Impact of diabetes mellitus on treatment outcome of newly diagnosed smear-positive pulmonary tuberculosis patients: A case–Control study. Med J DY Patil Vidyapeeth [Epub ahead of print] [cited 2023 Mar 20]. Available from: https://www.mjdrdypv.org/preprintarticle.asp?id=342631

  Introduction Top

The increase in the incidence of diabetes mellitus (DM) is an important risk and challenge to tuberculosis (TB) control.[1] The association between the two had been described many years ago by Avincenna, a Persian philosopher.[2] The link of DM and TB is more prominent in developing countries where TB is endemic, and the burden of DM is increasing.[3] The estimated annual incidence of TB in India is around 2.8 million which is estimated to be a quarter of global load.[4] Diabetics have a 2–3 times higher risk of developing active TB than nondiabetics.[5] Diabetic patients with TB have an increased risk of death and failure during course of treatment and recurrent disease after treatment completion.[6]

In recent decades, with the increasing prevalence of TB, particularly multidrug-resistant TB, and DM cases in the world, the relationship is raising its head as a significant public health problem.

Aims and objectives

  1. This study aims to compare the sputum smear conversion between diabetic TB and nondiabetic TB patients treated under the Revised National TB Control Program (RNTCP)
  2. To compare the treatment success rate between diabetic TB and nondiabetic TB patients treated under RNTCP.

  Materials and Methods Top

The study was designed as a case–control study and conducted from October 2019 to September 2020 in a tertiary care hospital of eastern India. Information collected from the patients was as follows:

Age (n = 120), gender (n = 120), sputum smear status (n = 120), sputum smear grading (n = 120), sputum cartridge-based nucleic acid amplification test (CBNAAT) (n = 120), history of diabetes new/known (n = 60), diabetic treatment status (n = 60), details of diabetic medications (n = 60), random blood sugar (n = 120), fasting blood sugar (FBS) (n = 120), postprandial blood sugar (PPBS) (n = 120), and glycosylated hemoglobin (HbA1C) (n = 120).

The study population included sixty cases of new smear-positive PTB with a history of DM or newly diagnosed DM. Another sixty patients with new smear-positive PTB without DM formed the control group. An informed consent was obtained from all the patients. The patients belonged to the age group of 18–64 years. Patients with drug-resistant TB (as evidenced by initial CBNAAT), chronic kidney disease or chronic liver disease, HIV-positive status, <18 years of age or more than 64 years of age, and those who refused to give consent were excluded from the study.

All the patients in the study group were started on injectable insulin after consultation with the endocrinologist. The smear status was followed up at the end of intensive phase (IP) and at treatment completion with sputum smear examination. FBS, 2-h PPBS was repeated monthly, and HbA1C was repeated every 3 months till completion of antitubercular treatment.

The definitions used regarding disease profile and treatment outcomes were according to RNTCP guidelines.[7]

Smear conversion at the end of intensive phase

Two negative sputum smears at the end of IP of treatment.

Treatment success

Patients declared as cured or treatment completed.

All patients both of case and control group received category I directly observed treatment shortcourse.

The criteria for diagnosis of DM by the American Diabetes Association8 were followed:

FPG ≥126 mg/dL (7.0 mmol/L) or

2-h PG ≥200 mg/dL (11.1 mmol/L) during an OGTT or

HbA1C ≥6.5% (48 mmol/L) or

In a patient with classic symptoms of hyperglycemia or hyperglycemic crisis, a random plasma glucose was ≥200 mg/dL (11.1 mmol/L).[8]

All the data were recorded using Microsoft Excel. The statistical software, namely SPSS Statistics for Windows, version 16.0. (SPSS Inc., Chicago, Ill., USA), was used to analyze all the data. The study was approved by Institutional Ethical Committee.

  Results Top

There were sixty patients each in the study and control group, respectively. The mean age and body weight among cases were 52.03 ± 7.24 years and 58.23 ± 7.78 kg, respectively, whereas in control group, these were 36.32 ± 13.34 years and 55.11 ± 7.95 kg, respectively [Table 1]. Males and females among cases were 48 (80%) and 12 (20%), respectively, whereas in control group, they were 41 (68.3%) and 19 (31.7%), respectively.
Table 1: Demographic and laboratory data

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The mean duration of diabetes among cases was 4.18 ± 2.64 years. The mean FBS level at diagnosis (FBS0) in cases was 211.5 ± 63.5 mg/dl whereas in case of control group was 80.6 ± 9.4 mg/dl (P = 0.01). The mean HbA1C level at diagnosis (HbA1C0) was 11.9% ± 1.48% among cases which was higher than control group, where it is 4.8% ± 0.59% (P = 0.01).

There were 25 (41.7%) cases and 14 (23.3%) patients of control group having 3+ sputum grading at diagnosis (P = 2.14). Sputum smear conversion was seen in 24 (40%) cases as compared to 55 (91.7%) patients in control group [Table 2]. Thus, the control group had 19.47 times higher chance of smear conversion as compared to cases (odds ratio [OR]: 19.47; 95% confidence interval [CI]: 6.2–61.0; P: 0.001).
Table 2: Comparison of smear conversion between cases and control

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Treatment success was observed in 40 (66.7%) out of 60 cases versus 56 (93.3%) out of 60 controls [Table 3]. Treatment success rate was 10.23 times higher in control group as compared to cases (OR = 10.231; 95% CI = 2.35–36.66; P = 0.001).
Table 3: Comparison of treatment outcome between cases and control

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A total of 51 patients in the study group had a poorly controlled DM. Smear conversion was observed in 21 (41.7%) out of the 51 poorly controlled DM patients (HbA1C ≥7.1%) versus 3 (42.8%) out of 7 well controlled and newly diagnosed DM patients (HbA1C ≤7%) (OR: 1.26; 95% CI: 0.8–1.8; P: 1.22) [Table 4].
Table 4: Comparison of smear conversion among controlled and poorly controlled diabetes mellitus

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  Discussion Top

The sputum smear conversion was 40% and treatment success rate was 66.7% among new smear-positive TB cases with DM which were suboptimal as per the target set by RNTCP7. The results from a previous systematic review by Baker et al. on studies done worldwide in diabetic TB patients were heterogeneous with the relative risk ranging from 0.79 to 3.25 for sputum conversion.[6] A study from Maharashtra reported significantly lower sputum conversion rates among PTB patients with diabetes (76.5%) compared to those without diabetes (92.7%) under TB Control Program settings.[9] An earlier study in Tamil Nadu by Viswanathan and Gawde has reported that smear-positive PTB patients with diabetes were less likely to have successful treatment outcomes and have documented higher proportion of treatment failure among diabetic TB patients.[10] The present study is concordant with these studies regarding smear conversion and treatment outcomes among TB-DM patients. A study conducted by Banurekha et al. showed 86% successful treatment outcomes of all new diabetic TB patients observed.[11]

In our study, the treatment outcome was low compared to the 90% target of RNTCP for the 12th 5-year plan (2012–2017). However, Viswanathan and Gawde,[10] in their study found the success rates to be very similar for new smear-positive patients: 90% for diabetics and 91.9% for nondiabetics.

Some explanations for worse outcome among diabetics are higher rates of drug resistance, impaired cellular immunity, delay in sputum conversion, and lower plasma levels of anti-TB drugs; the last may be explained by increased weight of DM patients or excess weight gain during TB treatment without an accurate adjustment of drug dosing in the later phase of treatment.[12],[13] Another explanation was given by Bashar et al. suggested that diabetic patients have some degree of impaired gastrointestinal drug absorption, even in the absence of clinical gastroparesis.[14] Not only that, but the hyperglycemic state may also additionally interfere with achieving adequate tissue levels of the medications or interfere with alveolar macrophage or CD4+ cell function.

In the present study, there is no significant difference in smear conversion between well controlled (42.8%) and poorly controlled DM (41.7%).

  Conclusion Top

Smear conversion and treatment success rate among diabetic TB patients were significantly lower as compared to nondiabetic TB patients. There is no difference in smear conversion between controlled and poorly controlled diabetic TB patients. However, a strict diabetic control should be aimed in all patients to prevent associated complications due to the disease itself that may affect the treatment regimen and outcome.


  1. Small sample size
  2. The management and outcome of patients with treatment failure were not included in the study.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

  References Top

Ottmani SE, Murray MB, Jeon CY, Baker MA, Kapur A, Lönnroth K, et al. Consultation meeting on tuberculosis and diabetes mellitus: Meeting summary and recommendations. Int J Tuberc Lung Dis 2010;14:1513-7.  Back to cited text no. 1
Boucot KR, Dillon ES, Cooper DA, Meier P, Richardson R. Tuberculosis among diabetics: The Philadelphia survey. Am Rev Tuberc 1952;65:1-50.  Back to cited text no. 2
Baghaei P, Marjani M, Javanmard P, Tabarsi P, Masjedi MR. Diabetes mellitus and tuberculosis facts and controversies. J Diabetes Metab Disord 2013;12:58.  Back to cited text no. 3
Indian TB Report 2018: Revised National TB Control Programme – Annual Status Report. Available from: https://tbcindia.gov.in/showfile.php?lid=3314. [Last accessed on 2020 Oct 18].  Back to cited text no. 4
Jeon CY, Murray MB. Diabetes mellitus increases the risk of active tuberculosis: A systematic review of 13 observational studies. PLoS Med 2008;5:e152.  Back to cited text no. 5
Baker MA, Harries AD, Jeon CY, Hart JE, Kapur A, Lönnroth K, et al. The impact of diabetes on tuberculosis treatment outcomes: A systematic review. BMC Med 2011;9:81.  Back to cited text no. 6
Revised National TB Control Programme. Training Module for Medical Practitioners. Central TB Division. Directorate General of Health Services. Ministry of Health and Family Welfare. Available from: http://www.tbcindia.nic.in/index1. [Last accessed on 2020 Oct 24].  Back to cited text no. 7
American Diabetes Association. Erratum. Diabetes care in the hospital. Sec. 14. In standards of medical care in diabetes-2017. Diabetes Care 2017;40(Suppl 1);S120-S127. Diabetes Care 2017;40:986.  Back to cited text no. 8
Shital P, Anil J, Sanjay M, Mukund P. Tuberculosis with diabetes mellitus: Clinical-radiological overlap and delayed sputum conversion needs cautious evaluation-prospective cohort study in tertiary care hospital, India. J Pulm Respir Med 2014;4:175.  Back to cited text no. 9
Viswanathan AA, Gawde NC. Effect of type II diabetes mellitus on treatment outcomes of tuberculosis. Lung India 2014;31:244-8.  Back to cited text no. 10
[PUBMED]  [Full text]  
Banurekha V, Bhatnagar T, Savithri S, Kumar ND, Kangusamy B, Mehendale S. Sputum conversion and treatment success among tuberculosis patients with diabetes treated under the tuberculosis control programme in an urban setting in South India. Indian J Community Med 2017;42:180-2.  Back to cited text no. 11
[PUBMED]  [Full text]  
Ruslami R, Aarnoutse RE, Alisjahbana B, van der Ven AJ, van Crevel R. Implications of the global increase of diabetes for tuberculosis control and patient care. Trop Med Int Health 2010;15:1289-99.  Back to cited text no. 12
Young F, Critchley J, Unwin N. Diabetes & tuberculosis: A dangerous liaison & no white tiger. Indian J Med Res 2009;130:1-4.  Back to cited text no. 13
[PUBMED]  [Full text]  
Bashar M, Alcabes P, Rom WN, Condos R. Increased incidence of multidrug-resistant tuberculosis in diabetic patients on the Bellevue Chest Service, 1987 to 1997. Chest 2001;120:1514-9.  Back to cited text no. 14


  [Table 1], [Table 2], [Table 3], [Table 4]


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