Correlation between Sputum Cartridge-based Nucleic Acid Amplification Test–Cycle Threshold Values and Glycosylated Hemoglobin Levels in Patients with Pulmonary Tuberculosis

Aims and background: India bears the brunt of both tuberculosis (TB) as well as diabetes patients globally, and either disease affects each other detrimentally, leading to increased morbidity and mortality; thereby, hampering the national and international policies and goals targeted in the control and prevention of these diseases. Hence, this study was done to determine the correlation between the sputum cartridge-based nucleic acid amplification test (CBNAAT) cycle threshold (Ct) values and glycosylated hemoglobin (HbA1c) levels at the point of diagnosing pulmonary tuberculosis (PTB). Materials and methods: This study, conducted over a span of 6 months, followed a cross-sectional design. Patients diagnosed with PTB, confirmed by sputum CBNAAT, were enrolled in the study after screening them with the inclusion and exclusion criteria. The sputum CBNAAT Ct values were noted, and the average of the five probes labeled as A, B, C, D, and E was utilized to quantify the bacilli, reported as the mean Ct value. Semi-quantitative mycobacterial load results were categorized as follows—high (Ct values <16), medium (Ct values 16–22), low (Ct values 22–28), or very low (Ct values >28). The HbA1c (glycated hemoglobin) levels of the patients were estimated from a venous blood sample. Results: Out of 136 study subjects, 61% were male participants with a mean age of 41 years. Among them, 23.5% (<italic>n</italic> = 32) were previously known diabetics. Additionally, 37.5% (<italic>n</italic> = 51) were newly detected diabetics based on HbA1c levels (cutoff 6.4) at the time of PTB diagnosis. Most patients had a low bacterial load (44.10%, <italic>n</italic> = 60). The high bacterial load group (26.5%, <italic>n</italic> = 36) had the lowest mean Ct value of 15.51, while the very low bacterial load group (8%, <italic>n</italic> = 8) had the highest mean Ct value of 31.47. The high bacterial load group also had the highest mean HbA1c level of 7.6, whereas the low bacterial load group had the lowest mean HbA1c level of 6.03. The Pearson correlation coefficient is −0.426, indicating a moderate negative correlation between the two variables. Conclusion: This study found a moderate negative correlation between sputum CBNAAT Ct values and HbA1c levels in patients with pulmonary TB. This suggests that as HbA1c levels increase, the bacillary load also increases, as indicated by decreasing Ct values, and vice versa. Clinical significance: According to our study, patients with poor glycemic control have a high bacterial load, predicting more severe disease. This finding may help guide treatment decisions and improve patient outcomes.