Effect of glycemic control on tuberculosis treatment outcomes among patients with tuberculosis and diabetes mellitus:A systematic review and meta-analysis

Introduction: Tuberculosis (TB) and diabetes mellitus comorbidity can lead to poor TB treatment outcomes, particularly with uncontrolled blood glucose levels. Understanding the impact of glycemic control on TB treatment outcomes is essential. Objective: To synthesise evidence on the association between glycemic control and TB treatment outcomes in patients with TB and diabetes mellitus. Methodology: A systematic review was conducted using Medline, Embase, Scopus, Web of Science, Cumulative Index to Nursing and Allied Health Literature (CINAHL) and Google Scholar for all types of studies published between 1975 and May 2024, including adult TB patients of >18 years of age, with or without diabetes mellitus for whom blood glucose testing along with TB treatment outcome comparison with glucose levels (low/high) was reported were considered for inclusion. A random-effects model was used for meta-analysis, heterogeneity was assessed using I-squared statistics, subgroup and sensitivity analysis was performed followed by publication bias assessment. Results: Of 576 identified studies, 12 met the inclusion criteria, analysing 2320 cases (1572 with uncontrolled high blood glucose [≥7% HbA1c] and 748 with controlled low blood glucose [<7% HbA1c]). Low certainty evidence shows that patients with uncontrolled high glucose had a 1.91 times higher risk of TB treatment failure (risk ratios [RR] = 1.91, 95% confidence interval [CI] 1.81–3.07, p = 0.008), and a 2.97 times higher risk of sputum positivity at 3 months (RR = 2.97, 95% CI 1.10–8.07, p = 0.03). Subgroup and sensitivity analyses showed significant improvement in pooled effects, lowering of heterogeneity and narrower CIs. For overall pooled effect, substantial heterogeneity was observed; therefore, the interpretation and generalisation of results should be done with caution. Conclusion: A low certainty evidence shows that uncontrolled high blood glycemic level significantly impacts TB treatment outcomes, increasing treatment failure and sputum positivity among TB patients with diabetes mellitus.