The International Journal of Mycobacteriology

ORIGINAL ARTICLE
Year
: 2021  |  Volume : 10  |  Issue : 2  |  Page : 111--115

Treatment outcomes of patients with tuberculosis and diabetes: A prospective cohort study from India


Ananya Desai1, Nitin Gupta2, Lakshmi Korishetty3, Kavitha Saravu2,  
1 Department of 1Medicine, Kasturba Medical College, Manipal Academy of Higher Education, Manipal, Karnataka, India
2 Department of Infectious Diseases, Kasturba Medical College, Manipal Academy of Higher Education; Manipal Center for Infectious Diseases, Prasanna School of Public Health, Manipal Academy of Higher Education, Manipal, Karnataka, India
3 Department of Medicine, Kasturba Medical College, Manipal Academy of Higher Education, Manipal, Karnataka, India

Correspondence Address:
Kavitha Saravu
Department of Infectious Diseases, Kasturba Medical College, Manipal Academy of Higher Education, Manipal - 576 104, Karnataka
India

Abstract

Introduction: Tuberculosis (TB) and diabetes mellitus (DM) are significant causes of morbidity and mortality in developing countries. This study aimed to explore the relationship between diabetes and TB. Methods: This was a prospective cohort study in which all newly diagnosed inpatients with TB above the age of 18 years during the study period (September 2018 to August 2020) were included. Fasting sugars and glycosylated hemoglobin (HbA1c) levels were recorded at the baseline, 3rd month, and 6th month in the diabetic patients on antitubercular therapy (ATT). Treatment outcomes were measured in both the diabetic and the nondiabetic groups. Results: The prevalence of diabetes in patients with TB admitted at our tertiary care hospital was found to be 38.5%. A favorable treatment outcome was seen in 96.3% of the patients with DM when compared to 95.6% in those without diabetes. A decreasing trend of HbA1c and fasting sugars was noticed in patients with DM during ATT. Conclusion: The screening of DM in patients with TB can help in early diagnosis and better glycemic control which may improve the possibility of favorable outcomes.



How to cite this article:
Desai A, Gupta N, Korishetty L, Saravu K. Treatment outcomes of patients with tuberculosis and diabetes: A prospective cohort study from India.Int J Mycobacteriol 2021;10:111-115


How to cite this URL:
Desai A, Gupta N, Korishetty L, Saravu K. Treatment outcomes of patients with tuberculosis and diabetes: A prospective cohort study from India. Int J Mycobacteriol [serial online] 2021 [cited 2021 Sep 23 ];10:111-115
Available from: https://www.ijmyco.org/text.asp?2021/10/2/111/307069


Full Text



 Introduction



The worldwide prevalence of diabetes mellitus (DM) is enormous, and by the year 2030, it is expected to increase up to 550 million.[1] According to a report, there are 463_million people with DM in the world with 88 million located in the South-East Asian regions.[2] India is currently home to nearly one-third of global tuberculosis (TB) burden with 77 million people diagnosed with diabetes.[2] DM, being an immune-compromised state, has been identified as a major risk factor for many infectious diseases, including TB and mucormycosis.[3],[4] In diabetic patients, infections such as TB usually worsen the glycemic control, and uncontrolled diabetes invariably enhances the gravity of the infection. TB, among other infections, can cause impairment of glucose control and predisposes patients to DM. In a country like India, where the dual burden of both these diseases is high, the interaction among them becomes a major challenge to the health system.[1] The objectives of the study were to determine the prevalence of DM in TB patients, to determine the treatment outcomes of TB patients with DM, and to estimate the trends of glycosylated hemoglobin (HbA1c) levels in patients with TB and DM on antitubercular therapy (ATT).

 Methods



A prospective study was conducted at Kasturba Hospital, a tertiary care hospital in the southern part of India. All hospitalized adult patients >18 years with newly diagnosed with pulmonary TB (PTB) and extrapulmonary tuberculosis (EPTB) between September 2018 to August 2020 were included in the study. Those patients who have been already started on ATT for >15 days were excluded from the study. A case was considered as PTB if the sputum of the patient tested positive for acid-fast bacillus staining, cartridge-based nucleic acid testing, or culture. A case was considered EPTB if there were clinical, radiological, and pathological features suggestive of tubercular involvement of sites other than the lung. Patients were considered as diabetic if they had a fasting plasma glucose (FBS) >126 mg/dl or HbA1c >6.5% at the time of diagnosis. Both newly diagnosed diabetics and those on treatment were included.

A brief clinical history and the underlying comorbid conditions of patients satisfying the inclusion criteria were obtained. Clinical parameters, such as height, weight, and body mass index (BMI), were noted. The method for diagnosis of TB was recorded in all patients. The baseline investigations of FBS and HbA1c levels were recorded for all patients. The patients were followed up for a response to ATT. A case was considered “cured” if the positive sputum smear or culture became negative by the end of treatment. A case was considered “treatment completed” if the treatment was completed and there was no clinical evidence of failure but in whom microbiological evidence of cure could not be obtained. A “defaulter” was a patient whose treatment was interrupted for 2 consecutive months while “treatment failure” was defined as persistent positivity of sputum smear or culture at 5 months. A case was considered as lost to follow-up if one failed to follow up after initiation of treatment. “Cured” and “treatment completed” were considered as “favorable outcome” while the rest were considered as “unfavorable outcome.” The trend of FBS and HbA1c levels was also charted by measuring them on the 3rd and 6th months in diabetics.

Data analysis

The data analysis was done using Excel and IBM SPSS Statistics for Windows, version 25 (IBM Corp., Armonk, N.Y., USA). Those variables with normal distribution were expressed as mean ± standard deviation), and the baseline characteristics of the population were compared by Chi-square/Fisher's exact test. Post hoc analysis was done to compare pairwise time point, and Mann–Whitney U-test was used to compare HbA1c levels in the PTB and EPTB groups.

 Results



A total of 286 patients who were newly diagnosed with TB at our hospital during the study period were enrolled consecutively. A total of 172 (60.1%) patients had PTB, and 114 (39.9%) patients had EPTB. In EPTB, pleural effusion (34%) was most common followed by lymphadenitis (19%), abdominal TB (17%), musculoskeletal TB (12.2%), neurological TB (10.5%), genitourinary TB (3.5%), and TB pericarditis (2.6%).

Out of the 286 patients, 110 patients (38.5%) had DM. Out of the 110 patients who were diabetics, 80.9% (89) patients had a known history of diabetes, and 19.1% (21) were newly diagnosed diabetics. The mean duration of the history of diabetes was 6.2 ± 1.89 years. A total of 41 (37.3%) patients required insulin treatment and 69 (62.7%) patients were only on oral antidiabetics. In patients with DM, baseline HbA1c ranged between 5.7% and 15% with the majority of the patients having HbA1c between 7.2% and 11.05%. The median HbA1c at baseline in diabetics was 9.19 (interquartile range [IQR] = 7.2%–11%). HbA1c among patients without DM in the study cohort ranged between 4.4% and 6.4% with the majority of the patients having HbA1c between 5.2% and 5.8%. The median HbA1c at baseline in nondiabetics was 5.43 (IQR = 5.2%–5.8%).

The baseline characteristics and method of diagnosing TB patients with diabetes and nondiabetics are summarized in [Table 1]. PTB was more common in diabetics when compared to nondiabetics [Table 1]. DM was more prevalent in TB patients in the age group of 41–60 years with a mean age of 45.2 years ± 0.8 [Table 1]. There was a higher prevalence of TB-DM among males than females [Table 1]. There was no significant difference in the BMI between diabetics and nondiabetics [Table 1]. History of smoking and alcohol was more commonly seen in diabetics [Table 1]. History of ischemic heart disease was more common in diabetics [Table 1].{Table 1}

Out of the 286 patients, a total of 173 patients (60.5%) were followed up at our hospital. The rest of the patients chose to continue their treatment at a nearby government center of Directly Observed Treatment Short-Course (DOTS) Chemotherapy. Their follow-up details are not available. The treatment outcomes of TB patients with and without DM are summarized in [Table 2].{Table 2}

The mean FBS for PTB and EPTB patients at baseline was 200.3 ± 92.6 and 158.6 ± 60.8, respectively. The mean HbA1c for PTB and EPTB patients at baseline was 9.5 ± 2.3 and 8.3 ± 2, respectively. The FBS and HbA1c in diabetic patients (both PTB and EPTB) on ATT showed a decreasing trend on follow-up at the 3rd and the 6th months. The mean change in FBS and HbA1c was found to be significantly higher in the PTB group when compared to the EPTB group [Table 3].{Table 3}

 Discussion



Although the association between TB and DM was suggested for long, the recognition of this dual epidemic has come to light only recently.[3] DM is a chronic disease with hyperglycemia resulting in oxidative stress and tissue damage as well as impairment in immunity, predisposing individuals to TB.[5] TB, on the other hand, has been observed to cause disruption of glycemic control, thereby predisposing to DM. The World Health Organization has, therefore, recommended for bidirectional screening to tackle this looming epidemic of diabetes and TB.[6]

Our cohort included admitted patients who were newly diagnosed with TB. It was observed that TB patients with DM were predominantly male and between the age group of 41 and 50 years, similar to other studies from India.[7],[8],[9] A study from Nigeria also showed that males are generally reported to have a higher risk of TB-DM than females.[10] This could be due to a higher prevalence of smoking and alcohol intake in males. In our study, history of smoking and alcohol was more commonly found in diabetics when compared to nondiabetics. Some of the previous studies have shown a significantly higher BMI in diabetic patients with TB when compared to nondiabetics.[9] In contrast, Kumpatla et al. reported a lower mean BMI in the TB-DM group as compared to nondiabetics with TB.[11] Few other studies, similar to our study, have shown that no significant correlation was found between BMI and TB-DM.[7]

Our study cohort showed a higher prevalence of DM at 38.5%, which could be due to the possible selection bias as only hospitalized patients were included. Previous studies have shown that hospitalized TB patients have a significantly higher prevalence of DM compared to patients receiving outpatient care.[12],[13] Other studies done from India have shown an estimated prevalence of DM in TB varying between 19.2% and 32.2%.[7],[14],[15] In our study, PTB was more common in diabetics compared to nondiabetics. Previous studies conducted in India,[14] Brazil,[16] the United States of America, and China[17] have shown similar results. A credible mechanism explaining this particular association has not yet been adequately described.

In a systematic review done by Baker et al.,[18] it was observed that treatment outcomes were poor in diabetics. In a study from Malaysia, DM was found to be a significant risk factor for persistence of sputum positivity in the 2nd month of treatment.[19] In a study from Dubai, DM was found to be a risk factor of TB drug resistance as well.[20] However, in a study done in Kerala, India,[21] there was no statistical significance observed between the treatment outcomes in TB patients with and without DM. In our study, the treatment outcomes of TB were comparable between the diabetics and nondiabetics. This could have been because the study was conducted in a tertiary care hospital where quality care was available for the patients, and good follow-up was ensured.

Glycemic control plays an important role in determining the prognosis of TB treatment. The mean HbA1c levels and FBS showed a decreasing trend on follow-up in most patients. Similar findings have been noticed in other studies as well.[22],[23] The change was more pronounced in PTB patients when compared to EPTB. This could have been because of the higher baseline levels of FBS and HbA1C in PTB patients compared to EPTB patients. There were seven patients with an unfavorable response in this study. Out of these seven, six died during the first admission, and therefore, their follow-up could not be done. Since the number of patients with an unfavorable response to ATT was very less and follow-up could not be done due to early death, the trend of sugars and HbA1c between those with the favorable and unfavorable response could not be compared.

Limitations

The follow-up details of 113 patients were not available as they chose to follow up with the government DOTS center.

 Conclusion



The prevalence of DM in patients with TB is high, especially in patients with PTB. The treatment outcomes with ATT were observed to be comparable in patients with diabetic and nondiabetic cohorts. The screening of DM in patients with TB can help in early diagnosis and better glycemic control which may improve the possibility of favorable outcomes.

Ethical clearance

Ethical clearance was obtained prior to the study. IEC number: 645/2018 (Date 10th October 2018).

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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