Diabetes screen during tuberculosis contact investigations highlights opportunity for new diabetes diagnosis and reveals metabolic differences between ethnic groups

Picking the low-hanging fruit: the cost-effectiveness of opportunistic diabetes screening during tuberculosis contact investigations on the Texas-Mexico border

Objective

There is a known association between type 2 diabetes (diabetes) and tuberculosis (TB), and TB clinics have become hubs for new diabetes diagnosis among active patients with TB. However, despite the potential to identify diabetes patients, resources limit diabetes screening opportunities to close TB contacts. We assessed the cost-effectiveness of adding opportunistic screening for diabetes during the routine TB contact investigations conducted at TB clinics.

Research design and methods

We used a Markov-based model to simulate the costs of diabetes screening, management and health outcomes, including the incidence of complications and death. All costs were considered from a health system perspective. One-way sensitivity analyses were conducted to assess the robustness of the results to various assumptions. Interventions that fall below US$50 000 per quality-adjusted life years (QALYs) are commonly considered very cost-effective, while those between $50 000 and $100 000 are considered moderately cost-effective.

Results

Simulation of diabetes screening among TB contacts resulted in not only increased survival and reduced complications but also increased costs of diabetes management. The resulting incremental cost-effectiveness ratio was $32 642 per QALY added, which is well within commonly used willingness-to-pay thresholds for cost-effectiveness. Compared with no screening, screening increased the costs by $8633 and resulted in an increase in QALYs by 0.26 per patient.

Conclusions

In the base case analysis, screening was very cost-effective given that none of the sensitivity analyses resulted in a cost-effectiveness ratio above $50 000 per QALY. Our results indicate that the expansion of diabetes screening in TB clinics is a cost-effective strategy to improve health outcomes.

HUMAN ALVEOLAR MACROPHAGE FUNCTION IS IMPAIRED IN TUBERCULOSIS CONTACTS WITH DIABETES

Type 2 diabetes (T2D) increases susceptibility to tuberculosis (TB) with the underlying mechanisms remaining unknown. To determine whether immune dysfunction in the lung contributes to TB susceptibility, we obtained paired human alveolar macrophages (HAMs) and monocyte-derived macrophages (MDMs) from TB-exposed individuals with/without T2D. Upon infection with Mycobacterium tuberculosis (M.tb), T2D-HAMs had more M.tb growth and produced more TNF. There were fewer neutrophils in the bronchoalveolar lavage of T2D patients which was inversely correlated with M.tb growth. Both T2D-HAMs and MDMs expressed less CD32, with T2D patients having fewer M1-like MDMs. T2D-MDMs produced less IL-1RA and CSF2. Overall M.tb-induced gene expression was delayed in T2D-HAMs, but genes involved in negative regulation of neutrophil migration were upregulated. T2D-HAM DNA was hypermethylated compared to control HAMs, however genes linked to TNF signalling were hypomethylated. We show here the first in-depth analysis of T2D-HAMs providing an explanation for more severe TB in T2D patients.

Prevalence of non-communicable diseases among household contacts of people with tuberculosis: A systematic review and individual participant data meta-analysis

OBJECTIVE

To investigate the prevalence of non-communicable diseases among household contacts of people with tuberculosis.

METHODS

We conducted a systematic review and individual participant data meta-analysis. We searched Medline, Embase and the Global Index Medicus from inception to 16 May 2023. We included studies that assessed for at least one non-communicable disease among household contacts of people with clinical tuberculosis. We estimated the non-communicable disease prevalence through mixed effects logistic regression for studies providing individual participant data, and compared it with estimates from aggregated data meta-analyses. Furthermore, we compared age and sex-standardised non-communicable disease prevalence with national-level estimates standardised for age and sex.

RESULTS

We identified 39 eligible studies, of which 14 provided individual participant data (29,194 contacts). Of the remaining 25 studies, 18 studies reported aggregated data suitable for aggregated data meta-analysis. In individual participant data analysis, the pooled prevalence of diabetes in studies that undertook biochemical testing was 8.8% (95% confidence interval [CI], 5.1%-14.9%, four studies). Age-and sex-standardised prevalence was higher in two studies (10.4% vs. 6.9% and 11.5% vs. 8.4%) than the corresponding national estimates and similar in two studies. Prevalence of diabetes mellitus based on self-report or medical records was 3.4% (95% CI 2.6%-4.6%, 14 studies). Prevalence did not significantly differ compared to estimates from aggregated data meta-analysis. There were limited data for other non-communicable diseases.

CONCLUSION

The prevalence of diabetes mellitus among household contacts was high while that of known diabetes was substantially lower, suggesting the underdiagnosis. tuberculosis household contact investigation offers opportunities to deliver multifaceted interventions to identify tuberculosis infection and disease, screen for non-communicable diseases and address shared risk factors.

HIV, malnutrition, and noncommunicable disease epidemics among tuberculosis-affected households in east and southern Africa: A cross-sectional analysis of the ERASE-TB cohort

BACKGROUND

As a result of shared social and structural risk factors, people in households affected by tuberculosis may have an increased risk of chronic conditions; at the same time, tuberculosis screening may be an opportunity for interventions. We sought to describe the prevalence of HIV, nutritional disorders, and noncommunicable diseases (NCDs) among members of tuberculosis-affected households in 3 African countries.

METHODS AND FINDINGS

A part of a multicountry cohort study, we screened for tuberculosis, HIV, nutritional disorders (underweight, anaemia, overweight/obesity), and NCDs (diabetes, hypertension, and chronic lung disease) among members of tuberculosis-affected households aged ≥10 years in Mozambique, Tanzania, and Zimbabwe. We describe the prevalence of these conditions, their co-occurence within individuals (multimorbidity) and household-level clustering. Of 2,109 household contacts recruited, 93% (n = 1,958, from 786 households) had complete data and were included in the analysis. Sixty-two percent were female, median age was 27 years, and 0.7% (n = 14) were diagnosed with co-prevalent tuberculosis. Six percent of household members (n = 120) had previous tuberculosis, 15% (n = 294) were living with HIV, 10% (n = 194) had chronic lung disease, and 18% (n = 347) were anaemic. Nine percent of adults (n = 127) had diabetes by HbA1c criteria, 32% (n = 439) had hypertension. By body mass index criteria, 18% household members (n = 341) were underweight while 29% (n = 549) were overweight or obese. Almost half the household members (n = 658) had at least 1 modifiable tuberculosis risk factor. Sixty-one percent of adults (n = 822) had at least 1 chronic condition, 1 in 4 had multimorbidity. While most people with HIV knew their status and were on treatment, people with NCDs were usually undiagnosed and untreated. Limitations of this study include use of point-of-care HbA1c for definition of diabetes and definition of hypertension based on single-day measurements.

CONCLUSIONS

Households affected by tuberculosis also face multiple other health challenges. Integrated approaches to tuberculosis screening may represent an opportunity for identification and treatment, including prioritisation of individuals at highest risk for tuberculosis to receive preventive therapy.

Characterizing poorly controlled type 2 diabetes using 1H-NMR metabolomics

INTRODUCTION

The prevalence of type 2 diabetes has surged to epidemic proportions and despite treatment administration/adherence, some individuals experience poorly controlled diabetes. While existing literature explores metabolic changes in type 2 diabetes, understanding metabolic derangement in poorly controlled cases remains limited.

OBJECTIVE

This investigation aimed to characterize the urine metabolome of poorly controlled type 2 diabetes in a South African cohort.

METHOD

Using an untargeted proton nuclear magnetic resonance metabolomics approach, urine samples from 15 poorly controlled type 2 diabetes patients and 25 healthy controls were analyzed and statistically compared to identify differentiating metabolites.

RESULTS

The poorly controlled type 2 diabetes patients were characterized by elevated concentrations of various metabolites associated with changes to the macro-fuel pathways (including carbohydrate metabolism, ketogenesis, proteolysis, and the tricarboxylic acid cycle), autophagy and/or apoptosis, an uncontrolled diet, and kidney and liver damage.

CONCLUSION

These results indicate that inhibited cellular glucose uptake in poorly controlled type 2 diabetes significantly affects energy-producing pathways, leading to apoptosis and/or autophagy, ultimately contributing to kidney and mild liver damage. The study also suggests poor dietary compliance as a cause of the patient's uncontrolled glycemic state. Collectively these findings offer a first-time comprehensive overview of urine metabolic changes in poorly controlled type 2 diabetes and its association with secondary diseases, offering potential insights for more targeted treatment strategies to prevent disease progression, treatment efficacy, and diet/treatment compliance.

A pilot cross-sectional study of non-communicable diseases in TB household contacts

BACKGROUND

Data on the prevalence of non-communicable diseases (NCDs) in TB household contacts (HHCs) are limited, yet important to inform integrated screening and care for NCD within contact investigations. It is also unclear if screening these contacts reveals more people with NCDs than individuals in the same neighbourhood.

METHOD

We conducted a pilot cross-sectional study in South Africa and Tanzania, enrolling adult HHCs of TB and individuals in neighbourhood households (controls). We inquired about known NCD and systematically measured blood pressure, and tested for spot blood glucose and haemoglobin A1c.

RESULTS

We enrolled 203 adult contacts of 111 persons with TB and 160 controls. Among contacts, respectively 12.2% (95% CI 8.3-17.6) and 39.7% (95% CI 33.1-46.7) had diabetes and hypertension, compared to 14.1% (95% CI 9.2-21.0) and 44.7% (95% CI 36.9-52.7) among controls. More than half of NCDs were newly identified. We did not find a significant difference in the prevalence of at least one NCD between the two groups (OR 0.85, 95% CI 0.50-1.45, adjusted for age and sex).

CONCLUSIONS

We found a high prevalence of undiagnosed NCDs among contacts, suggesting a potential benefit of integrating NCD screening and care within contact investigations. Screening in the same community might similarly find undiagnosed NCDs.

Tobacco smoking clusters in households affected by tuberculosis in an individual participant data meta-analysis of national tuberculosis prevalence surveys: Time for household-wide interventions?

Tuberculosis (TB) and non-communicable diseases (NCD) share predisposing risk factors. TB-associated NCD might cluster within households affected with TB requiring shared prevention and care strategies. We conducted an individual participant data meta-analysis of national TB prevalence surveys to determine whether NCD cluster in members of households with TB. We identified eligible surveys that reported at least one NCD or NCD risk factor through the archive maintained by the World Health Organization and searching in Medline and Embase from 1 January 2000 to 10 August 2021, which was updated on 23 March 2023. We compared the prevalence of NCD and their risk factors between people who do not have TB living in households with at least one person with TB (members of households with TB), and members of households without TB. We included 16 surveys (n = 740,815) from Asia and Africa. In a multivariable model adjusted for age and gender, the odds of smoking was higher among members of households with TB (adjusted odds ratio (aOR) 1.23; 95% CI: 1.11-1.38), compared with members of households without TB. The analysis did not find a significant difference in the prevalence of alcohol drinking, diabetes, hypertension, or BMI between members of households with and without TB. Studies evaluating household-wide interventions for smoking to reduce its dual impact on TB and NCD may be warranted. Systematically screening for NCD using objective diagnostic methods is needed to understand the actual burden of NCD and inform comprehensive interventions.

Differential Role of Type 2 Diabetes as a Risk Factor for Tuberculosis in the Elderly versus Younger Adults

The elderly are understudied despite their high risk of tuberculosis (TB). We sought to identify factors underlying the lack of an association between TB and type 2 diabetes (T2D) in the elderly, but not adults. We conducted a case-control study in elderly (≥65 years old; ELD) vs. younger adults (young/middle-aged adults (18-44/45-64 years old; YA|MAA) stratified by TB and T2D, using a research study population (n = 1160) and TB surveillance data (n = 8783). In the research study population the adjusted odds ratio (AOR) of TB in T2D was highest in young adults (AOR 6.48) but waned with age becoming non-significant in the elderly. Findings were validated using TB surveillance data. T2D in the elderly (vs. T2D in younger individuals) was characterized by better glucose control (e.g., lower hyperglycemia or HbA1c), lower insulin resistance, more sulphonylureas use, and features of less inflammation (e.g., lower obesity, neutrophils, platelets, anti-inflammatory use). We posit that differences underlying glucose dysregulation and inflammation in elderly vs. younger adults with T2D, contribute to their differential association with TB. Studies in the elderly provide valuable insights into TB-T2D pathogenesis, e.g., here we identified insulin resistance as a novel candidate mechanism by which T2D may increase active TB risk.

Diabetes-Associated Susceptibility to Tuberculosis: Contribution of Hyperglycemia vs. Dyslipidemia

Diabetes is a major risk factor for tuberculosis (TB). Diabetes increases the risk of the progression from latent tuberculosis infection (LTBI) to active pulmonary TB and TB patients with diabetes are at greater risk of more severe disease and adverse TB treatment outcomes compared to TB patients without co-morbidities. Diabetes is a complex disease, characterised not only by hyperglycemia but also by various forms of dyslipidemia. However, the relative contribution of these underlying metabolic factors to increased susceptibility to TB are poorly understood. This review summarises our current knowledge on the epidemiology and clinical manifestation of TB and diabetes comorbidity. We subsequently dissect the relative contributions of body mass index, hyperglycemia, elevated cholesterol and triglycerides on TB disease severity and treatment outcomes. Lastly, we discuss the impact of selected glucose and cholesterol-lowering treatments frequently used in the management of diabetes on TB treatment outcomes.

A prospective cross-sectional study of tuberculosis in elderly Hispanics reveals that BCG vaccination at birth is protective whereas diabetes is not a risk factor

BACKGROUND

Aging increases the risk of tuberculosis (TB) and its adverse outcomes, but most studies are based on secondary analyses, and few are in Hispanics. Diabetes is a risk factor for TB in adults, but its contribution in the elderly is unknown. We aimed to identify the role of diabetes and other risk factors for TB in elderly Hispanics.

METHODS

Cross-sectional study among newly-diagnosed TB patients, recent contacts (ReC), or community controls (CoC) totaling 646 participants, including 183 elderly (>60 years; 43 TB, 80 ReC, 60 CoC) and 463 adults (18 to 50 years; 80 TB, 301 ReC and 82 CoC). Host characteristics associated with TB and latent Mycobacterium tuberculosis infection (LTBI) were identified in the elderly by univariable and confirmed by multivariable logistic regression.

RESULTS

LTBI was more prevalent among the elderly CoC (55% vs. 23.2% in adults; p<0.001), but not in ReC (elderly 71.3% vs. adult 63.8%); p = 0.213). Risk factors for TB in the elderly included male sex (adj-OR 4.33, 95% CI 1.76, 10.65), smoking (adj-OR 2.55, 95% CI 1.01, 6.45) and low BMI (adj-OR 12.34, 95% CI 4.44, 34.33). Unexpectedly, type 2 diabetes was not associated with TB despite its high prevalence (adj-OR 0.38, 95% CI 0.06, 2.38), and BCG vaccination at birth was protective (adj-OR 0.16, 95% CI 0.06, 0.45).

CONCLUSIONS

We report novel distinctions in TB risk factors in the elderly vs. adults, notably in diabetes and BCG vaccination at birth. Further studies are warranted to address disparities in this vulnerable, understudied population.

Pre-Diabetes Increases Tuberculosis Disease Severity, While High Body Fat Without Impaired Glucose Tolerance Is Protective

Type 2 diabetes (T2D) is a well-known risk factor for tuberculosis (TB), but little is known about pre-diabetes and the relative contribution of impaired glucose tolerance vs. obesity towards susceptibility to TB. Here, we developed a preclinical model of pre-diabetes and TB. Mice fed a high fat diet (HFD) for 12 weeks presented with impaired glucose tolerance and hyperinsulinemia compared to mice fed normal chow diet (NCD). Infection with M. tuberculosis (Mtb) H₃₇R_v after the onset of dysglycemia was associated with significantly increased lung pathology, lower concentrations of TNF-α, IFN-γ, IFN-β and IL-10 and a trend towards higher bacterial burden at 3 weeks post infection. To determine whether the increased susceptibility of pre-diabetic mice to TB is reversible and is associated with dysglycemia or increased body fat mass, we performed a diet reversal experiment. Pre-diabetic mice were fed a NCD for 10 additional weeks (HFD/NCD) at which point glucose tolerance was restored, but body fat mass remained higher compared to control mice that consumed NCD throughout the entire experiment (NCD/NCD). Upon Mtb infection HFD/NCD mice had significantly lower bacterial burden compared to NCD/NCD mice and this was accompanied by restored IFN-γ responses. Our findings demonstrate that pre-diabetes increases susceptibility to TB, but a high body mass index without dysglycemia is protective. This murine model offers the opportunity to further study the underlying immunological, metabolic and endocrine mechanisms of this association.

Hyperglycemia and dyslipidemia: Reduced HLA-DR expression in monocyte subpopulations from diabetes patients

Immune dysfunction contributes to the higher risk of communicable and non-communicable diseases among diabetics. HLA-DR expression is a robust marker of immune competence in mononuclear cells, including antigen presentation to CD4 lymphocytes. Given the high prevalence of obesity among diabetics, we evaluated the independent association between hyperglycemia and dyslipidemias with respect to HLA-DR expression in blood monocytes from type 2 diabetes patients. The monocytes from individuals with (n = 16) or without diabetes (n = 25) were phenotyped by flow cytometry to assess the differential expression of HLA-DR on their three subpopulations (classical, intermediate and non-classical monocytes). Diabetes was independently associated with lower HLA-DR expression across all monocyte subpopulations (p < 0.05). Blood triglycerides were associated with further HLA-DR depression (interaction p < 0.002). Cholesterols counterbalanced the reductive effect, with CD36, a receptor for oxidized cholesterol, correlating with HLA-DR (rho = 0.373; p = 0.016). Future studies are warranted to elucidate the complex interactions between hyperglycemia and dyslipidemias on antigen presentation in diabetic monocytes.

Human monocyte-derived macrophage responses to M. tuberculosis differ by the host's tuberculosis, diabetes or obesity status, and are enhanced by rapamycin

Human macrophages play a major role in controlling tuberculosis (TB), but their anti-mycobacterial mechanisms remain unclear among individuals with metabolic alterations like obesity (TB protective) or diabetes (TB risk). To help discern this, we aimed to: i) Evaluate the impact of the host's TB status or their comorbidities on the anti-mycobacterial responses of their monocyte-derived macrophages (MDMs), and ii) determine if the autophagy inducer rapamycin, can enhance these responses. We used MDMs from newly diagnosed TB patients, their close contacts and unexposed controls. The MDMs from TB patients had a reduced capacity to activate T cells (surrogate for antigen presentation) or kill M. tuberculosis (Mtb) when compared to non-TB controls. The MDMs from obese participants had a higher antigen presenting capacity, whereas those from chronic diabetes patients displayed lower Mtb killing. The activation of MDMs with rapamycin led to an enhanced anti-mycobacterial activity irrespective of TB status but was not as effective in patients with diabetes. Further studies are warranted using MDMs from TB patients with or without metabolic comorbidities to: i) elucidate the mechanisms through which host factors affect Mtb responses, and ii) evaluate host directed therapy using autophagy-inducing drugs like rapamycin to enhance macrophage function.

GPR183 Regulates Interferons, Autophagy, and Bacterial Growth During Mycobacterium tuberculosis Infection and Is Associated With TB Disease Severity

Oxidized cholesterols have emerged as important signaling molecules of immune function, but little is known about the role of these oxysterols during mycobacterial infections. We found that expression of the oxysterol-receptor GPR183 was reduced in blood from patients with tuberculosis (TB) and type 2 diabetes (T2D) compared to TB patients without T2D and was associated with TB disease severity on chest x-ray. GPR183 activation by 7α,25-dihydroxycholesterol (7α,25-OHC) reduced growth of Mycobacterium tuberculosis (Mtb) and Mycobacterium bovis BCG in primary human monocytes, an effect abrogated by the GPR183 antagonist GSK682753. Growth inhibition was associated with reduced IFN-β and IL-10 expression and enhanced autophagy. Mice lacking GPR183 had significantly increased lung Mtb burden and dysregulated IFNs during early infection. Together, our data demonstrate that GPR183 is an important regulator of intracellular mycobacterial growth and interferons during mycobacterial infection.

The re-emerging association between tuberculosis and diabetes: Lessons from past centuries

The association between tuberculosis (TB) and diabetes mellitus (DM) had a common place in the literature up to the first half of the 20th century, but virtually disappeared with the discovery of insulin to treat DM and antibiotics to cure TB. In the late 1990s the literature began to re-emerge with the worldwide increase in type 2 DM, particularly in TB-endemic countries. Today, type 2 DM is the most prevalent comorbidity among TB patients and the World Health Organization considers it a threat to TB control. We summarize the literature on TB and DM up to the 1960s. Then we evaluate unique aspects of this comorbidity in older times, such as the frequent diabetic comas that suggest challenges for proper DM management as insulin was being implemented, or the absence of antibiotics to cure TB. Despite the unique aspects of each study period, the literature across times is consistent in key aspects of the association. Namely, a higher TB prevalence among DM (versus non-DM patients), the importance of glucose control and chronic DM on TB susceptibility and the higher risk of death among patients with the co-morbidity. From the older literature, we can infer the likely contribution of type 1 DM to TB (in addition to type 2), regardless of their differing autoimmune or metabolic pathophysiology, respectively. Furthermore, in the older literature there was a notable reporting of DM development among TB patients, even though DM usually preceded TB. This observation deserves further epidemiological and basic studies to elucidate this intriguing aspect of the relationship between TB and DM.

Diabetes, undernutrition, migration and indigenous communities: tuberculosis in Chiapas, Mexico

We investigated the distribution of comorbidities among adult tuberculosis (TB) patients in Chiapas, the poorest Mexican state, with a high presence of indigenous population, and a corridor for migrants from Latin America. Secondary analysis on 5508 new adult TB patients diagnosed between 2010 and 2014 revealed that the most prevalent comorbidities were diabetes mellitus (DM; 19.1%) and undernutrition (14.4%). The prevalence of DM in these TB patients was significantly higher among middle aged (41-64 years) compared with older adults (⩾65 years) (38.6% vs. 23.2%; P < 0.0001). The prevalence of undernutrition was lower among those with DM, and higher in communities with high indigenous presence. Immigrants only comprised 2% of all TB cases, but were more likely to have unfavourable TB treatment outcomes (treatment failure, death and default) when compared with those born in Chiapas (29.5% vs. 11.1%; P < 0.05). Unfavourable TB outcomes were also more prevalent among the TB patients with undernutrition, HIV or older age, but not DM (P < 0.05). Our study in Chiapas illustrates the challenges of other regions worldwide where social (e.g. indigenous origin, poverty, migration) and host factors (DM, undernutrition, HIV, older age) are associated with TB. Further understanding of these critical factors will guide local policy makers and health providers to improve TB management.