Impact of Diabetes and Low Body Mass Index on Tuberculosis Treatment Outcomes

Abstract

Background Diabetes was identified as a tuberculosis (TB) risk factor mostly in retrospective studies with limited assessments of metabolic variables. The prospective Effects of Diabetes on Tuberculosis Severity study compared adults with pulmonary TB in Chennai, India, who were classified as having either diabetes or a normal glucose tolerance at enrollment. Methods Baseline TB severity, sputum conversion, and treatment outcomes (cure, failure, death, or loss to follow-up) were compared between groups with respect to glycemic status and body mass index (BMI). Results The cohort of 389 participants included 256 with diabetes and 133 with a normal glucose tolerance. Low BMIs (<18.5 kg/m2) were present in 99 (74.4%) of nondiabetic participants and 85 (33.2%) of those with diabetes. Among participants with normal or high BMIs, rates of cure, treatment failure, or death did not vary by glycemic status. Participants with low BMIs had the highest radiographic severity of disease, the longest time to sputum culture conversion, and the highest rates of treatment failure and death. Among participants with low BMIs, poorly controlled diabetes (glycohemoglobin [HbA1c] ≥8.0%) was unexpectedly associated with better TB treatment outcomes. A high visceral adiposity index was associated with adverse outcomes and, despite an overall correlation with HbA1c, was elevated in some low-BMI individuals with normal glucose tolerance. Conclusions In this South Indian cohort, a low BMI was significantly associated with an increased risk for adverse TB treatment outcomes, while comorbid, poorly controlled diabetes lessened that risk. A high visceral adiposity index, either with or without dysglycemia, might reflect a novel TB susceptibility mechanism linked to adipose tissue dysfunction.

Diabetes Mellitus and Tuberculosis Treatment Outcomes in Pune, India

“…In contrast to several retrospective reports and a systematic review in LMICs [ 8 , 11 , 27 ], our prospective analysis does not indicate an independent association between DM and composite unfavorable TB treatment outcome, consistent with a recent report from South India [ 28 ]. Traditional risk factors such as low BMI [ 29 , 30 ] and alcohol use [ 31 ] were associated with adverse outcomes; neither degree of hyperglygemia nor new DM was associated with unfavorable outcomes [ 28 ].…”

“…In contrast to several retrospective reports and a systematic review in LMICs [ 8 , 11 , 27 ], our prospective analysis does not indicate an independent association between DM and composite unfavorable TB treatment outcome, consistent with a recent report from South India [ 28 ]. Traditional risk factors such as low BMI [ 29 , 30 ] and alcohol use [ 31 ] were associated with adverse outcomes; neither degree of hyperglygemia nor new DM was associated with unfavorable outcomes [ 28 ]. We found that low and normal BMI were more common among TB-DM participants than high BMI, a finding explained by studies that find that Indians generally have higher visceral adiposity index than their Western counterparts with the same body weight, leading to a high burden of insulin resistance, even among normal- or low-bodyweight Indians [ 28 , 32 ].…”

“…Traditional risk factors such as low BMI [ 29 , 30 ] and alcohol use [ 31 ] were associated with adverse outcomes; neither degree of hyperglygemia nor new DM was associated with unfavorable outcomes [ 28 ]. We found that low and normal BMI were more common among TB-DM participants than high BMI, a finding explained by studies that find that Indians generally have higher visceral adiposity index than their Western counterparts with the same body weight, leading to a high burden of insulin resistance, even among normal- or low-bodyweight Indians [ 28 , 32 ]. However, as reported previously, we also found a non–statistically significant directionality between low BMI and DM and adverse treatment outcomes [ 28 ].…”

Slow radiological improvement and persistent low-grade inflammation after chemotherapy in tuberculosis patients with type 2 diabetes

“…Although, our data analyses were adjusted for these confounders, the differences in baseline demographics may still have influenced the treatment outcome in this patient cohort. It was recently observed that TB patients in India with a low BMI had a considerably longer time to sputum culture conversion and enhanced rates of treatment failure and death when compared to patients with a normal-to-high BMI (independent of DM status) [53]. Thus, demographic variables such as BMI or socioeconomic status might obscure the negative effects of DM on TB.…”

Infections and diabetes: Risks and mitigation with reference to India

“…However, Nandakumar et al [ 44 ] found no correlation between diabetes control and TB treatment outcomes in their study conducted in Malappuram district of Kerala. In this context, it is interesting to note that recent studies have shown an association of poorly controlled diabetes with better outcomes in individuals with low body-mass index; this needs confirmation in larger studies [ 45 ].…”