Impact of tuberculosis on glycaemic status: A neglected association

Diabetes mellitus (DM) is an important risk factor for tuberculosis and has received increasing emphasis. However, the reverse association of tuberculosis impacting blood sugar levels has not been well studied. The present study was conducted to evaluate the prevalence of hyperglycemia in patients with tuberculosis and assess its resolution following successful treatment of tuberculosis.

In this prospective study, a total of 582 patients with tuberculosis were evaluated for hyperglycaemia [DM or impaired glucose tolerance (IGT)] with random blood sugar (RBS) and all patients with RBS >100 mg/dl were subjected to a 75 g oral glucose tolerance test (OGTT). All patients received thrice weekly intermittent Directly Observed Treatment Short Course (DOTS) for tuberculosis. Patients with hyperglycaemia were re-evaluated at the end of anti-tuberculosis treatment with an OGTT and glycated hemoglobin (HbA_1c) levels to assess for glycaemic status.

In the present study, 41 of the 582 patients were found to have DM [7%, 95% confidence interval (CI) (5.2, 9.4)] while 26 patients were found to have IGT [4.5%, 95% CI (3, 6.5)]. Three patients were lost to follow up. Of the 26 patients with IGT, 17 [65.4%, 95% CI (46.1, 80.7)] reverted to euglycaemic status following successful treatment of tuberculosis, while the blood sugar levels improved in all patients with DM following treatment of tuberculosis.

Our study results show that tuberculosis adversely impacts glycaemic status with improvement in blood sugar levels at the end of successful treatment of tuberculosis. Longitudinal studies with large sample size are required to confirm these findings.