Study design

We carried out a prospective cohort study in two counties, Kiambu and Nairobi, in Kenya between February 2014 and August 2015. Patients aged above15 years who tested positive for Mycobacterium tuberculosis complex on sputum smear microscopy and were not pregnant at the time of diagnosis were eligible to participate. Ethical approval for the study was obtained from the Kenyatta National Hospital Ethical Research Committee (KNH/UoN-ERC) and the study was undertaken in accordance with the principles of the Helsinki Declaration.

Written consent was obtained from patients who agreed to participate. Venous blood drawn was collected at baseline in two separate tubes (one for fasting or random blood glucose levels and the other for HbA1c levels). This was followed by physical examination and questionnaire administration by trained healthcare personnel where detailed history, including signs and symptoms of diabetes mellitus, cigarette smoking and other life-style information were ascertained. Patients were then followed at two, three, five and six months and at end of therapy to assess adherence and clinical evaluation with sputum microscopy examination at each time when possible. The initial sputum examination was submitted for culture and pathogen identification. Patients were examined at each visit for both TB and DM.