Diabetes Linked to Tuberculosis Risk
Diabetes status may play a role in the risk for developing tuberculosis, suggests a new study reported in JAMA Network Open.
Diabetes and tuberculosis are two major problems for South Africa; an estimated 15% of the population 25 and over have type 2 diabetes, and the burden of tuberculosis was 774 per 100k population in 2012.
In the population-based study from Korea, adults with diabetes had a 48% greater risk for developing tuberculosis compared with adults without diabetes.
This increased tuberculosis risk also appeared to be tied to the duration of diabetes, with risk increasing the longer the person had diabetes:
- New-onset diabetes: aHR 1.32 (95% CI 1.23-1.42)
- Diabetes duration less than 5 years: aHR 1.45 (95% CI 1.36-1.54)
- Diabetes duration 5 or more years: aHR 1.57 (95% CI 1.48-1.66)
The tuberculosis risk also seemed to be dependent on blood glucose levels. Individuals with impaired fasting glucose only, that is, blood glucose levels of 100-125 mg/dL but no diabetes diagnosis, did not appear to have an elevated risk of contracting tuberculosis.
However, those with new-onset diabetes in the highest decile of fasting blood glucose levels (202 mg/dL or higher) had a 79% greater risk for tuberculosis than those with lower glucose levels (fasting plasma glucose of 126-128 mg/dL).
The researchers noted that a previous study looking at this association found about a 2.2-fold increased risk of tuberculosis in patients with diabetes, including those with a fasting plasma glucose level over 130 mg/dL.
“Diabetes appears to be associated with increased risk of lower respiratory tract infection, including TB [tuberculosis], and to have a profound adverse effect on TB treatment outcomes,” the researchers explained. “Even though TB is more associated with other immunosuppressive states, such as human immunodeficiency virus infection, because of the greater numbers, diabetes remains an important factor associated with TB incidence at the population level.”
For the cohort study, the researchers drew upon data from the Korean National Health Insurance System database. Only patients without a history of tuberculosis were included. Besides a history of tuberculosis, other exclusion criteria included diagnoses of anaemia, cancer, and end-stage renal disease.
Individuals who had diabetes the longest tended to be older, have obesity, and possess more comorbidities like chronic kidney disease, chronic obstructive pulmonary disease, ischaemic heart disease, stroke, and dyslipidaemia.
During a median follow-up of about 8 years, 0.6% of the cohort were identified.
A study limitation was that fasting plasma glucose levels were only monitored once at baseline, and that changes in glucose level after treatment was over were not taken into consideration.
“Nevertheless, it is likely that patients whose diabetes status progressed as a result of poor glucose control during the follow-up duration would have a higher risk of TB,” the researchers wrote.
The link with tuberculosis was stronger in male patients, they noted: “The exact mechanism for this phenomenon is not fully explainable — testosterone could be a reason.”
Source: MedPage Today
