Metformin shield against tuberculosis.

Metformin: The Unsung Hero for Diabetics in the Fight Against Tuberculosis

Beau Callahan in Health & Wellness December 2025 • 4 min read.

"New research reveals how this common diabetes drug could significantly lower TB risk, offering a beacon of hope for millions."

Tuberculosis (TB) continues to be a global health threat, especially for individuals with diabetes mellitus (DM). People with diabetes are more prone to TB due to compromised immunity, making them three times more likely to develop active TB. With the number of people with diabetes expected to rise to 642 million by 2040, finding ways to mitigate this risk is crucial.

Now, a new nationwide cohort study offers a glimmer of hope. Researchers have found that metformin, a common medication used to manage diabetes, is associated with a lower risk of TB in diabetic patients with normal renal function. This unexpected benefit could lead to new strategies for preventing TB in this vulnerable population.

This article will delve into the details of this research, exploring how metformin could offer a dual advantage for those managing diabetes, and what this means for public health.

How Metformin Lowers TB Risk: Key Findings

The study, conducted using data from the Taiwan National Health Insurance Research Database (NHIRD), examined a large cohort of newly diagnosed DM patients. Researchers compared metformin users (those with >90 cumulative defined daily doses within one year) with propensity-score-matched nonusers to assess the impact on TB incidence.

The results revealed a significant association between metformin use and a reduced risk of active TB. Specifically, the study found:

Metformin use was independently associated with a 16% lower risk of incident TB (hazard ratio [HR]: 0.84 [0.74–0.96]).
A dose-response relationship was observed: higher doses of metformin (>150 cumulative DDDs) were linked to a greater reduction in TB risk (HR: 0.83 [0.72-0.97]).
The protective effect of metformin remained even when considering a subpopulation without renal function impairment.

These findings suggest that metformin may offer a protective effect against TB in diabetic patients, adding another potential benefit to its well-established role in managing blood sugar levels.

Implications and Future Directions

This research provides compelling evidence for the potential of metformin as a host-directed therapy for TB prevention in diabetic patients. Given the global burden of both diseases, this finding could have significant implications for public health strategies.

Newly diagnosed diabetic patients without contraindications should receive metformin as an anti-diabetic medication, with potential additional benefit against TB. Healthcare professionals should consider prescribing metformin for primary prevention of active TB in DM patients if no contraindications exist.

While these results are promising, further research is needed to fully understand the mechanisms by which metformin may protect against TB, and to confirm these findings in other populations and settings. Additional clinical studies are needed to confirm the protective effect and the potential interaction between these HDT drugs.

About this Article -

This article was crafted using a human-AI hybrid and collaborative approach. AI assisted our team with initial drafting, research insights, identifying key questions, and image generation. Our human editors guided topic selection, defined the angle, structured the content, ensured factual accuracy and relevance, refined the tone, and conducted thorough editing to deliver helpful, high-quality information.See our About page for more information.

This article is based on research published under:

DOI-LINK: 10.1371/journal.pone.0205807, Alternate LINK

Title: Metformin Use Is Associated With A Low Risk Of Tuberculosis Among Newly Diagnosed Diabetes Mellitus Patients With Normal Renal Function: A Nationwide Cohort Study With Validated Diagnostic Criteria

Subject: Multidisciplinary

Journal: PLOS ONE

Publisher: Public Library of Science (PLoS)

Authors: Ming-Chia Lee, Chen-Yuan Chiang, Chih-Hsin Lee, Cheng-Maw Ho, Chia-Hao Chang, Jann-Yuan Wang, Shih-Ming Chen

Published: 2018-10-18

Everything You Need To Know

How does metformin, a diabetes medication, potentially lower the risk of tuberculosis (TB)?

Metformin, a medication commonly prescribed for diabetes mellitus, has been shown to potentially reduce the risk of tuberculosis (TB) in diabetic patients. This is particularly important because individuals with diabetes mellitus are more susceptible to TB due to compromised immunity. The study suggests that by using metformin, diabetic patients, especially those with normal renal function, may gain an additional protective effect against developing active TB.

Does the dosage of metformin impact its effectiveness in reducing TB risk, and if so, what dosage is most effective?

The study indicates a dose-response relationship with metformin, meaning that higher doses of metformin, specifically those exceeding 150 cumulative defined daily doses, are associated with a greater reduction in TB risk. The research, however, does not specify an optimal dosage, and such decisions must be made by a healthcare provider considering individual patient needs and renal function.

How was the study conducted to determine the potential link between metformin use and reduced TB risk in diabetic patients?

The study used data from the Taiwan National Health Insurance Research Database (NHIRD), examining a large group of patients newly diagnosed with diabetes mellitus. Researchers compared diabetic patients who were metformin users (defined as those with over 90 cumulative defined daily doses within one year) to non-users, matching them using propensity scores to ensure comparability. This approach allowed them to assess the impact of metformin on tuberculosis incidence.

What are the broader public health implications of the research findings regarding metformin and TB risk?

The findings suggest that metformin could be used as a host-directed therapy for TB prevention in patients with diabetes mellitus. This is significant given the increasing global prevalence of diabetes mellitus, which is expected to reach 642 million by 2040. Further research may explore combining metformin with existing TB prevention strategies to maximize effectiveness and reduce the overall burden of TB, especially in vulnerable populations.

Does metformin usage affect diabetic patients with impaired renal function regarding TB risk reduction?

The study specifically examined the impact of metformin on diabetic patients with normal renal function. While it found that metformin had a protective effect in this group, the research does not directly address its safety or efficacy in diabetic patients with impaired renal function. Therefore, it's crucial for healthcare providers to carefully consider renal function when prescribing metformin and to monitor patients for potential side effects.