Changes in glycosylated haemoglobin and treatment outcomes in patients with tuberculosis in Iran: a cohort study

Background: Diabetes mellitus (DM) affects tuberculosis (TB) treatment outcomes, mostly by increasing recurrence, mortality and treatment failure. The objectives were to determine the pattern of change in glycosylated haemoglobin (HbA1c) level in new TB patients admitted to hospital at the start and 3-months after TB treatment, and to relate the measurements at these two time intervals to whether patients successfully completed treatment. Methods: A prospective cohort study was conducted on hospitalized new TB patients at Masih Daneshvari Hospital from 2012 to 2013. All patients were tested for HbA1c at the beginning and 3 months after initiation of TB treatment. Changes in HbA1c were compared to TB treatment outcome. Results: There were 317 new TB cases admitted to hospital of which 158 had HbA1c at baseline and 3-months. Of these, 67 (42%) had normal values, 54 had an elevated HbA1c at either base-line or 3-months (uncertain diabetes status) and 37 (24%) had elevated HbA1c (>= 6.5%) at both time points (DM). There were differences between the groups: those with DM were older, had a known history of DM and a higher prevalence of cavities on chest x-ray. There were 150 (95%) patients who successfully completed treatment with no significant differences between the groups. Conclusion: There were changes in HbA1c during the first three-months of anti-TB treatment, but these were not associated with differences in TB treatment outcomes. Transient hyperglycemia should be considered in TB patients and needs to be taken into account in planning care and management.