Persistent Hyperglycaemia and Transient Dysglycaemia in Tuberculosis: Evaluating the Bidirectional Interaction With Type-2 Diabetes Mellitus and Clinical Outcomes

Introduction: Poor glycaemic control, indicated by a haemoglobin A1c (HbA1c) level of 7% or higher, increases the risk of active tuberculosis (TB) in patients with diabetes, while active TB can worsen glucose tolerance and insulin resistance, contributing to type-2 diabetes mellitus (DM) progression. The bidirectional relationship between TB and DM is well recognised, but the evolution of glycaemic status during TB treatment, particularly the distinction between transient and persistent dysglycaemia, is not well understood in high-burden settings. Methods: We conducted a prospective cohort study of 120 newly diagnosed pulmonary TB patients in Ghana, categorised as TB-Only (n = 66), TB with established DM on metformin (TB-DM_t, n = 39), and TB with dysglycaemia not requiring pharmacological therapy (TB-DM_nt, n = 15). HbA1c was measured at baseline, 3, 6 and 9 months. Results: TB-DM_t patients were older, had higher BMI and persistently elevated HbA1c (p < 0.001). In contrast, TB-DM_nt patients showed significant HbA1c decline during and after TB treatment, normalising by 6 months (p < 0.016). Most TB-Only patients maintained stable euglycaemia. Transient dysglycaemia resolved in TB-DM_nt, while persistent hyperglycaemia was confined to those with pre-existing DM (TB-DM_t). Conclusion: Routine HbA1c monitoring during TB therapy can distinguish transient dysglycaemia from true diabetes, supporting more precise risk stratification and tailored management of TB patients.