Introduction: The dual epidemic of Diabetes Mellitus (DM) and tuberculosis (TB) is a growing public health challenge in Sub-Saharan Africa (SSA), Uganda inclusive. Due to the immunologic dysfunction associated with diabetes mellitus, the odds of latent TB infection (LTBI) are increased in DM. This growth in DM burden is therefore projected to result in increase in TB burden and slow progress towards ending TB as a public health threat. Despite this observation, studies investigating the burden, immunologic profile, and factors associated with LTBI in the adult population with DM in Uganda are lacking. Objective: This study aimed to determine the prevalence, immunological profile, and factors associated with LTBI, among adults with diabetes mellitus attending the outpatient diabetes clinic at Kiruddu National Referral Hospital (KNRH). Methods: This was a cross-sectional study carried out at the outpatient diabetes clinic of KNRH. A total of 185 study participants were recruited by systematic random sampling. Relevant sociodemographic and clinical data was collected using a pre-tested case report form. All study participants underwent comprehensive clinical, laboratory, and radiological work up for DM, LTBI, active TB status, and immunological profiling. LTBI was defined as a positive QuantiFERON Gold in Tube Plus Test (QFT) result. The socio-demographic, clinical, and laboratory characteristics of participants with and without LTBI were compared and the differences in these characteristics were analysed using the Chi-square test for categorical data and the Mann Whitney-U test for continuous data. Multivariable logistic regression analysis was performed to identify the factors associated with LTBI. Results: We screened 186 study participants, of whom one was diagnosed with active TB and excluded. The median age was 50 (IQR = 42, 59) years, median HbA1c was 8.4% (IQR = 7.1%, 9.9%) and median duration since DM diagnosis was nine months (IQR = 5, 20 months). More than three quarters of study participants were female: 78.4% (145) were female; 30.8% (57) were aged 41 – 50 years, 33.5% (62) had been diagnosed with DM in less than six months, 87.6% (162) were on metformin therapy; 77.3% (143) had poor glycemic control with glycated hemoglobin A1c (HbA1c) levels greater than or equal to 7.0%, 5.4% (10) had Human Immunodeficiency virus (HIV), 41.1% (76) were obese (BMI ≥ 30kg/m2), 34.1% (63) had kidney dysfunction. Prevalence of LTBI was 57.8% (107/185). LTBI prevalence was higher among males than among females (65% vs 55.9%) without statistical significance. Compared to individuals aged less than 30 years old, individuals aged 51 – 60 years had higher odds of LTBI (OR = 8.10, p = 0.01, 95% CI = 1.59 – 41.21). Individuals with LTBI had lower CD8 counts (p = 0.02), lower white blood cell (WBC) and platelet counts (p = 0.02 and p = 0.01 respectively). Median absolute neutrophil to lymphocyte ratio (NLR), monocyte to lymphocyte ratio (MLR) and CD4 to CD8 ratios were similar between those with and without LTBI, while 11.9% (22), 6.0% (11) and 14.6% (27) of all participants had inverted CD4 to CD8 ratio, elevated NLR and elevated MLR. Conclusions and recommendations: LTBI is prevalent among adults with DM. Older individuals aged 51 – 60 years carry higher odds and should be prioritized for preventive therapy. LTBI in DM is associated with an immune suppression phenotype of lower absolute WBC and CD8 counts. We recommend further studies to describe temporal relationships between LTBI and immunological dysfunction (such as TB-specific interleukin-17 and tumor necrosis factor secretion by CD4 cells and monocytes) in DM.

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