Longer Diabetes Duration Associated with Higher Risk of Tuberculosis Incidence

The risk of TB was 48% higher in patients with diabetes compared to those without diabetes, while participants with IFG showed no increased risk of TB incidence.

Although an association between the risk of tuberculosis (TB) and diabetes status has been considered likely from previous epidemiological studies, there is not well established data on the consideration of impaired fasting glucose or duration of diabetes.

In a recent study, Dong Wook Shin, MD, Supportive Care Center, Sungkyunkwan University School of Medicine and colleagues investigated the risk of TB incidence according to diabetes status in a nationwide database.

They found a longer diabetes duration had a greater association with the development of TB, while patients with new-onset diabetes had a higher level of incident TB with a fasting plasma glucose (FPG) level of ≥202 mg/dL.

Methods

Investigators performed a population-based cohort study using data from the Korean National Health Insurance System database, which covers 97% of the Korean population.

The study included adult participants (n = 5,292,827) who underwent a health screening in 2009, without a history of TB. Patient exclusions included diagnosis of anemia, cancer, end-stage kidney disease, as well as patients with a history of TB or a new TB diagnosis.

In determining diabetes status at baseline, patients were classified according to glycemic status. The 5 categories included normal glucose (FPG <100 mg/dL, IFG (FPG 100 - 125 mg/dL), new-onset diabetes (FPG ≥126 mg/dL without diabetes diagnosis), diabetes duration <5 years, and diabetes duration ≥5 years.

Moreover, study participants were followed from baseline to date of TB diagnosis, censoring, or the end of the study period in December 2018. The primary outcome was considered a new TB diagnosis.

In patients with new-onset diabetes, the FPG level was categorized by decile, with decile 1 (lowest) showing <128 mg/DL and decile 10 (highest) showing ≥202 mg/dL.

Investigators used cox proportional hazards models to evaluate the association of diabetes status with TB incidence. Data analysis took place from September 2019 - September 2020.

Results

A total of 4,423,177 participants were included in the final study population, with a mean age of 46.5 years and 58.7% men (n = 2,597,142).

Data show the distribution of the study cohort included normal glucose (n = 3,030,004; 68.5%; IFG (n = 1,017,410; 23.0%); new-onset diabetes (n = 135,448, 3.1%); diabetes duration <5 years (n = 128 882, 2.9%); and diabetes duration ≥5 years (n = 111,433; 2.5%).

The team observed a total of 26,458 new cases of TB, consisting of 0.6% of the total population, over the median follow-up duration of 8.3 years.

Further, they saw the risk of TB was 48% higher in patients with diabetes compared to those without diabetes (adjusted hazard ratio aHR, 1.48; 95% CI. 1.42 - 1.53)

Additionally, participants with IFG showed no increased risk of TB incidence (aHR, 0.97; 95% CI, 0.93 - 1.01).

However, the risk of TB incidence was shown to increase with diabetes duration, consisting of new-onset diabetes (aHR, 1.32; 95% CI, 1.23 - 1.42), diabetes duration <5 years (aHR, 1.45; 95% CI, 1.36 - 1.54), diabetes duration ≥5 years (aHR, 1.57; 95% CI, 1.48 - 1.66).

A higher incidence of TB in patients with diabetes duration ≥5 years had strong associations in men (aHR, 1.84; 95% CI, 1.72 - 1.98) and younger participants aged <45 years (aHR, 4.61; 95% CI, 3.62 - 5.88).

Takeaways

Investigators concluded their results showed participants with diabetes had a 48% higher risk of TB incidence, while participants without diabetes and IFG had no increased risk for TB.

Additionally, they noted the association between diabetes and TB was stronger in patients with a longer diabetes duration.

“However, the effect of diabetes duration on TB risk has not been well established, and our study provides important implications that not only uncontrolled diabetes status but also diabetes duration can affect TB occurrence,” investigators wrote.

The study, “Diabetes Status and Association With Risk of Tuberculosis Among Korean Adults,” was published online in JAMA Network Open.