Pulmonary function tests in type 2 diabetes: a meta-analysis

The discrepant effect of blood glucose on the risk of early and late lung injury: a national cohort study

BACKGROUND

The association between glycemic control and short-, and long-term lung health remains controversial. This study aimed to investigate the relationship between glucose control and overall lung health in a national cohort.

METHODS

The analysis included 5610 subjects from NHANES 2007-2012. We assessed the correlation of glycemic status with respiratory symptoms (cough, sputum, wheeze, and exertional dyspnea), lung function (forced expiratory volume in 1-s (FEV1), forced vital capacity (FVC)), and obstructive or restrictive lung disease (RLD). Furthermore, we determined all-cause mortality in patients with restrictive lung disease by linking data to the National Mortality Index records up to December 31, 2019.

RESULTS

The study involved the examination of respiratory symptoms, pulmonary function tests, and mortality analyses encompassing 3714, 3916, and 173 subjects, respectively. Multifactorial regression analyses revealed that a 1% increase in blood glucose was associated with a reduction in effect sizes (β) for FVC and FEV1 by -1.66% (-2.47%, -0.86%) and -1.94% (-2.65%, -1.23%), respectively. This increase also exhibited correlations with an elevated risk of exertional dyspnoea, restrictive ventilation dysfunction, and all-cause mortality, presenting odds ratios (ORs) of 1.19 (1.06, 1.33), 1.22 (1.10, 1.36), and 1.61 (1.29, 2.01), respectively. Regarding glycemic control, patients with improved control demonstrated stronger associations with early lung damage, significantly correlating with reduced FVC (β -10.90%, [-14.45%, -7.36%]) and FEV1 (β -9.38%, [-12.90%, -5.87%]). Moreover, they experienced a notably higher risk of exertional dyspnoea (adjusted OR 2.09, [1.35- 3.24]), while the diabetic group with poorer glycemic control showed more significant connections with advanced lung damage. This group exhibited significant associations with an increased risk of restrictive ventilatory dysfunction (adjusted OR, 2.56, [1.70-3.86]) and all-cause mortality (hazard ratios [HRs] 2.65, [1.05-6.67]), all compared to the reference group with normal glycemic metabolism.

CONCLUSIONS

Elevated blood glucose exhibited an inverse correlation with both long-term and short-term lung health. A negative L-shaped relationship was observed between glycemic control and early lung injury, along with a linearly negative association concerning late-stage lung damage. Given the cross-sectional nature of this study, a longitudinal investigation is needed to validate our findings.

The Effects of Diabetes on Gas Transfer Capacity, Lung Volumes, Muscle Strength, and Cardio-pulmonary Responses During Exercise

BACKGROUND

Diabetes is a risk factor for the development of vascular disease, chronic kidney disease, retinopathy, and neuropathy. Diabetes is a co-morbid condition commonly present in patients with respiratory disorders but the extent to which it influences ventilatory capacity, gas exchange, and functional capacity is not well known. Research question Does the presence of diabetes contribute to impairment in spirometry, gas transfer, and exercise capacity?

METHODS

Retrospective analysis of all subjects who performed incremental cardio-pulmonary exercise testing (CPET) between 1988 and 2012 at McMaster University Medical Centre. The impact of diabetes on physiological outcomes and maximum power output (MPO) was assessed using stepwise multiple additive linear regression models including age, height, weight, sex, muscle strength, and previous myocardial infarct as co-variates, and was also stratified based on BMI categories.

RESULTS

40,776 subjects were included in the analysis; 1938 (5%, 66% male) had diabetes. Diabetics were older (59 vs. 53 years), heavier (88.3 vs.78.0 kg), and had a higher BMI (31 vs. 27 kg/m2). The presence of diabetes was independently associated with a reduction in FEV1 (- 130 ml), FVC (- 220 ml), DLCO (- 1.52 ml/min/mmHg), and VA (- 340ml) but not KCO. Patients with diabetes achieved a lower % predicted MPO[diabetic subjects 70% predicted (670 kpm/min ± 95% CI 284) vs. 80% in non-diabetics (786 kpm/min ± 342), p < 0.001]. With the exception of KCO, these differences persisted across BMI categories and after adjusting for MI.

CONCLUSION

The presence of diabetes is independently associated with weaker muscles, lower ventilatory and gas transfer capacity and translates to a lower exercise capacity. These differences are independent of age, height, weight, sex, and previous MI.

Cardiovascular and Respiratory Measures in Adults With Early-onset Type 2 Diabetes Mellitus Compared With Matched Controls

OBJECTIVES

The aim of the study was to compare cardiac and respiratory function at rest in participants with early-onset type 2 diabetes and a control group without diabetes, matched for age, sex, and body mass index (BMI).

METHODS

This study included 18 participants with early-onset type 2 diabetes (12 men and 6 women, age 34.9±6 years, diabetes duration 3.1±3.0 years) and 14 control participants without diabetes, matched for age, sex, and BMI (9 men and 5 women, age 32.9±5.2 years). Participants underwent resting echocardiography and pulmonary function tests. Fasting blood samples were analyzed for glycated hemoglobin, glucose, C-reactive protein, insulin, free fatty acids, and N-terminal pro-B-type natriuretic peptide.

RESULTS

Significant differences between groups were observed in left ventricular diastolic function at rest. Compared with controls, the group with early-onset type 2 diabetes had lower E/A (ratio between early [E] and late [A] ventricular filling velocity) (p=0.002), higher E/e' (representing left ventricular filling pressure) (p=0.017), lower e' (early myocardial relaxation velocity) (p<0.001), and lower diffusing capacity of the lung for carbon monoxide (p=0.003).

CONCLUSIONS

Subclinical left ventricular diastolic dysfunction and lower lung diffusing capacity were detected in participants with early-onset type 2 diabetes when compared with matched controls.

Evaluating the impact of type 2 diabetes mellitus on interstitial lung disease prevalence in patients with systemic lupus erythematosus: A national inpatient sample analysis

BACKGROUND

Systemic lupus erythematosus (SLE) increases the risk of interstitial lung disease (ILD). SLE is also linked to an elevated risk of type 2 diabetes mellitus (T2DM). However, the impact of T2DM on ILD risk in patients with SLE is still unclear. This study aimed to compare the prevalence of ILD in patients with SLE based on the presence of T2DM (SLE + T2DM+) or its absence (SLE + T2DM-).

METHODS

This was a retrospective cohort study using the 2019-2020 National Inpatient Sample database. Adult SLE patients were identified and stratified by T2DM status. Comparable cohorts were created using propensity score matching, resulting in 10,532 patients in each cohort. Multivariate logistic regression assessed the association between T2DM and ILD.

RESULTS

T2DM was associated with a lower prevalence of ILD in patients with SLE (OR 0.798, 95% CI: 0.695-0.918, p = .002), occurring in 371 (3.5%) patients with T2DM compared to 463 (4.4%) patients without T2DM. Specifically, this difference was mainly driven by pulmonary fibrosis, which was significantly less frequent in the T2DM group (1.3% vs 1.8%, OR 0.7, 95% CI: 0.560-0.875, p = .002). No differences were found in secondary outcomes, including death rates, length of hospital stay, ARDS, pneumothorax, pleural effusion, or pulmonary arterial hypertension.

CONCLUSION

Our study suggests that T2DM significantly reduced ILD risk in patients with SLE, specifically diminishing pulmonary fibrosis prevalence. Further research should explore mechanisms for this protective association between T2DM and ILD development in SLE. These findings may guide management strategies for this vulnerable population.

Cardiorespiratory dynamics of type 2 diabetes mellitus: An extensive view of breathing and fitness challenges in a diabetes prevalent population

BACKGROUND

Diabetes mellitus (DM) is well known for related micro and macrovascular complications. Uncontrolled hyperglycemia in diabetes mellitus leads to endothelial dysfunction, inflammation, microvascular impairment, myocardial dysfunction, and skeletal muscle changes which affect multiple organ systems. This study was designed to take an extensive view of cardiorespiratory dynamics in patients with type 2 DM.

METHODS

One hundred healthy controls (HC) and 100 DM patients were enrolled. We measured and compared the breathing patterns (spirometry), VO2 max levels (heart rate ratio method) and self-reported fitness level (international fitness scale) of individuals with and without diabetes. Data was analyzed in SPSS v.22 and GraphPad Prism v8.0.

RESULTS

We observed restrictive spirometry patterns (FVC <80%) in 22% of DM as compared to 2% in HC (p = 0.021). There was low mean VO2 max in DM as compared to HC(32.03 ± 5.36 vs 41.91 ± 7.98 ml/kg/min; p value <0.001). When evaluating physical fitness on self-reported IFiS scale, 90% of the HC report average, good, or very good fitness levels. In contrast, only 45% of the DM shared this pattern, with a 53% proportion perceiving their fitness as poor or very poor (p = <0.05). Restrictive respiratory pattern, low VO2 max and fitness level were significantly associated with HbA1c and long-standing DM.

CONCLUSION

This study shows decreased pulmonary functions, decreased cardiorespiratory fitness (VO2 max) and IFiS scale variables in diabetic population as compared to healthy controls which are also associated with glycemic levels and long-standing DM. Screening for pulmonary functions can aid optimum management in this population.

Deciphering the molecular mechanism of Bu Yang Huan Wu Decoction in interference with diabetic pulmonary fibrosis via regulating oxidative stress and lipid metabolism disorder

BACKGROUND

Diabetes mellitus type 2 and pulmonary fibrosis have been found to be closely related in clinical practice. Diabetic pulmonary fibrosis (DPF) is a complication of diabetes mellitus, but its treatment has yet to be thoroughly investigated. Bu Yang Huan Wu Decoction (BYHWD) is a well-known traditional Chinese prescription that has shown great efficacy in treating pulmonary fibrosis with hypoglycemic and hypolipidemic effects.

METHODS

The active ingredients of BYHWD and the corresponding targets were retrieved from the Traditional Chinese Medicine Systematic Pharmacology Database (TCMSP) and SymMap2. Disease-related targets were obtained from the GeneCard, OMIM and CTD databases. GO enrichment and KEGG pathway enrichment were carried out using the DAVID database. AutoDock Vina software was employed to perform molecular docking. Molecular dynamics simulations of proteinligand complexes were conducted by Gromacs. Animal experiments were further performed to validate the effects of BYHWD on the selected core targets, markers of oxidative stress, serum lipids, blood glucose and pulmonary fibrosis.

RESULTS

A total of 84 active ingredients and 830 target genes were screened in BYHWD, among which 56 target genes intersected with DPF-related targets. Network pharmacological analysis revealed that the active ingredients can regulate target genes such as IL-6, TNF-α, VEGFA and CASP3, mainly through AGE-RAGE signaling pathway, HIF-1 signaling pathway and TNF signaling pathway. Molecular docking and molecular dynamics simulations suggested that IL6-astragaloside IV, IL6-baicalein, TNFα-astragaloside IV, and TNFα-baicalein docking complexes could bind stably. Animal experiments showed that BYHWD could reduce the expression of core targets such as VEGFA, CASP3, IL-6 and TNF-α. In addition, BYHWD could reduce blood glucose, lipid, and MDA levels in DPF while increasing the activities of SOD, CAT and GSH-Px. BYHWD attenuated the expression of HYP and collagen I, mitigating pathological damage and collagen deposition within lung tissue.

CONCLUSIONS

BYHWD modulates lipid metabolism disorders and oxidative stress by targeting the core targets of IL6, TNF-α, VEGFA and CASP3 through the AGE-RAGE signaling pathway, making it a potential therapy for DPF.

Trajectory of lung function in diabetic adults: A 16-year follow-up study of community-based prospective cohorts

BACKGROUND AND OBJECTIVE

To investigate the difference in lung function according to diabetes status in a community-based prospective study.

METHODS

Individuals aged 40-69 years from two community-based cohorts were followed prospectively for 16 years. A spirometer was used to evaluate lung function at baseline, and lung function tests were carried out biennially thereafter. Multivariable linear regression analysis was performed for the cross-sectional and longitudinal analyses based on diabetes status.

RESULTS

Among the 6483 subjects, 2114 (32.6%) had prediabetes and 671 (10.4%) had diabetes. The prediabetes and diabetes groups had lower baseline % predicted values of forced expiratory volume in 1 s (FEV1) (mean, -1.853; 95% confidence interval [CI] -2.715 to -0.990 for prediabetes and mean, -4.088; 95% CI -5.424 to -2.752 for diabetes) and forced vital capacity (FVC) (mean, -2.087; 95% CI -2.837 to -1.337 for prediabetes and mean, -4.622; 95% CI -5.784 to -3.460 for diabetes) compared to the normoglycemia group after adjusting for relevant covariates. The rate of decline in FEV1% predicted (mean, -0.227; 95% CI -0.366 to -0.089) and FVC % predicted (mean, -0.232; 95% CI -0.347 to -0.117) during follow-up were faster in the diabetes group than in the normoglycemia group. The diabetes group had a lower proportion of normal ventilation (ptrend = 0.048) and higher proportions of restrictive (ptrend = 0.001) and mixed (ptrend = 0.035) ventilatory disorders at the last follow-up.

CONCLUSION

Diabetes is associated with a lower baseline lung function and a faster rate of deterioration.

Diabetes and lung function: Linked, but how?

See related article

Twenty-Four week Taichi training improves pulmonary diffusion capacity and glycemic control in patients with Type 2 diabetes mellitus

This study evaluated the effect of 24-week Taichi training and Taichi plus resistance band training on pulmonary diffusion capacity and glycemic control in patients with Type 2 diabetes mellitus (T2DM). Forty-eight patients with T2DM were randomly divided into three groups: Group A-Taichi training: practiced Taichi 60 min/day, 6 days/week for 24 weeks; Group B-Taichi plus resistance band training: practiced 60-min Taichi 4 days/week plus 60-min resistance band training 2 days/week for 24 weeks; and Group C-controls: maintaining their daily lifestyles. Stepwise multiple regression analysis was applied to predict diffusion capacity of the lungs for carbon monoxide (DLCO) by fasting blood glucose, insulin, glycosylated hemoglobin (HbA1c), tumour necrosis factor alpha (TNF-α), von Willebrand Factor (vWF), interleukin-6 (IL-6), intercellular adhesion molecule 1 (ICAM-1), endothelial nitric oxide synthase (eNOS), nitric oxide (NO), endothelin-1 (ET-1), vascular endothelial growth factor, and prostaglandin I-2. Taichi with or without resistance band training significantly improved DLCO, increased insulin sensitivity, eNOS and NO, and reduced fasting blood glucose, insulin, HbA1c, TNF-α, vWF, IL-6, ICAM-1, and ET-1. There was no change in any of these variables in the control group. DLCO was significantly predicted (R2 = 0.82) by insulin sensitivity (standard-β = 0.415, P<0.001), eNOS (standard-β = 0.128, P = 0.017), TNF-α (standard-β = -0.259, P = 0.001), vWF (standard-β = -0.201, P = 0.007), and IL-6 (standard-β = -0.175, P = 0.032) in patients with T2DM. The impact of insulin sensitivity was the most important predictor for the variation of DLCO based on the multiple regression modeling. This study demonstrates that 24-week Taichi training and Taichi plus resistance band training effectively improve pulmonary diffusion capacity and blood glycemic control in patients with T2DM. Variation of DLCO is explained by improved insulin sensitivity and endothelial function, and reduced inflammatory markers, including TNF-α, vWF, and IL-6.

Evaluating the Role of Glycemic Control in Modulating Pulmonary Function Among Smokers With Diabetes Mellitus: A Systematic Review

BACKGROUND

Diabetes mellitus (DM) impacts multiple body systems, including lung function, and this impact can be further complicated by smoking. The connection between blood sugar control and lung health in individuals with diabetes who smoke has been extensively studied, but findings have been varied. This systematic review sought to compile and assess the research on how blood sugar control influences lung function in smokers with diabetes.

METHODS

We searched several databases, including PubMed, EMBASE, Cochrane Library, Web of Science, Scopus, CINAHL, PsycINFO, and Google Scholar, in line with Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. We included studies that looked at lung function tests in smokers with diabetes and examined the relationship with blood sugar control, as indicated by hemoglobin A1c (HbA1c) levels. We conducted thorough quality assessments, data extraction, and analysis.

RESULTS

We identified five relevant studies. The data from these studies indicated a clear trend: smokers with diabetes who had higher HbA1c levels typically showed worse lung function than those with better blood sugar control. Decreases in forced expiratory volume in one second (FEV1) and forced vital capacity (FVC) were the most frequently observed issues. Some studies also pointed to a complex relationship between HbA1c levels and lung function, particularly when HbA1c was below 7.0%.

CONCLUSION

Our review indicates that smokers with DM who have poor blood sugar control tend to have worse lung function. These findings highlight the importance of managing blood sugar to help maintain lung health in these individuals. Further long-term research is needed to clarify the exact relationship and whether improving blood sugar control can reverse lung problems.

Pulmonary Function Trajectories Over 6 Years and Their Determinants in Type 2 Diabetes: The Fremantle Diabetes Study Phase II

OBJECTIVE

To assess whether there are clusters of people with type 2 diabetes with distinct temporal profiles of lung function changes and characteristics.

RESEARCH DESIGN AND METHODS

Group-based trajectory modeling (GBTM) identified groups of participants with type 2 diabetes from the community-based observational Fremantle Diabetes Study Phase II (FDS2) who had at least two biennial measurements of forced expiratory volume in 1 s as a percentage of predicted (FEV1%pred) over 6 years. Independent associates of group membership were assessed using multinomial regression.

RESULTS

Of 1,482 potential FDS2 participants, 1,074 (72.5%; mean age, 65.2 years; 45.5% female; median diabetes duration, 8.0 years) were included in the modeling. The best fitting GBTM model identified four groups categorized by FEV1%pred trajectory: high (19.5%; baseline FEV1%pred, 106.5 ± 9.5%; slope 0%/year), medium (47.7%; FEV1%pred, 87.3 ± 8.7%; slope, -0.32%/year), low (25.0%; baseline FEV1%pred, 68.9 ± 9.8%; slope, -0.72%/year), and very low (7.9%; baseline FEV1%pred, 48.8 ± 9.6%; slope, -0.68%/year). Compared with the high group, the other groups were characterized by nonmodifiable and modifiable risk factors associated with lung function decline in the general population (including ethnicity, marital status, smoking, obesity, coronary heart disease, and chronic respiratory disease). The main, diabetes-specific, significant predictor of group membership was a higher HbA1c in the very low group. There was a graded increase in mortality from 6.7% in the high group to 22.4% in the very low group.

CONCLUSIONS

Measurement of lung function in type 2 diabetes could help optimize clinical management and improve prognosis, including addressing glycemic control in those with a very low FEV1%pred.

Alpha-ketoglutarate supplementation reduces inflammation and thrombosis in type 2 diabetes by suppressing leukocyte and platelet activation

The interplay between platelets and leukocytes contributes to the pathogenesis of inflammation, thrombosis, and cardiovascular diseases (CVDs) in type 2 diabetes (T2D). Our recent studies described alpha-ketoglutarate (αKG), a Krebs cycle intermediate metabolite as an inhibitor to platelets and leukocytes activation by suppressing phosphorylated-Akt (pAkt) through augmentation of prolyl hydroxylase-2 (PHD2). Dietary supplementation with a pharmacological concentration of αKG significantly inhibited lung inflammation in mice with either SARS-CoV-2 infection or exposed to hypoxia treatment. We therefore investigated if αKG supplementation could suppress hyperactivation of these blood cells and reduce thromboinflammatory complications in T2D. Our study describes that dietary supplementation with αKG (8 mg/100 g body wt. daily) for 7 days significantly reduced the activation of platelets and leukocytes (neutrophils and monocytes), and accumulation of IL1β, TNFα, and IL6 in peripheral blood of T2D mice. αKG also reduced the infiltration of platelets and leukocytes, and accumulation of inflammatory cytokines in lungs by suppressing pAkt and pP65 signaling. In a cross-sectional investigation, our study also described the elevated platelet-leukocyte aggregates and pro-inflammatory cytokines in circulation of T2D patients. T2D platelets and leukocytes showed an increased aggregation and thrombus formation in vitro. Interestingly, a pre-incubation of T2D blood samples with octyl αKG significantly suppressed the activation of these blood cells and ameliorated aggregate/thrombus formation in vitro. Thus, suggesting a potential therapeutic role of αKG against inflammation, thrombosis, and CVDs in T2D.

Diabetic microvascular disease in non-classical beds: the hidden impact beyond the retina, the kidney, and the peripheral nerves

Diabetes microangiopathy, a hallmark complication of diabetes, is characterised by structural and functional abnormalities within the intricate network of microvessels beyond well-known and documented target organs, i.e., the retina, kidney, and peripheral nerves. Indeed, an intact microvascular bed is crucial for preserving each organ's specific functions and achieving physiological balance to meet their respective metabolic demands. Therefore, diabetes-related microvascular dysfunction leads to widespread multiorgan consequences in still-overlooked non-traditional target organs such as the brain, the lung, the bone tissue, the skin, the arterial wall, the heart, or the musculoskeletal system. All these organs are vulnerable to the physiopathological mechanisms that cause microvascular damage in diabetes (i.e., hyperglycaemia-induced oxidative stress, inflammation, and endothelial dysfunction) and collectively contribute to abnormalities in the microvessels' structure and function, compromising blood flow and tissue perfusion. However, the microcirculatory networks differ between organs due to variations in haemodynamic, vascular architecture, and affected cells, resulting in a spectrum of clinical presentations. The aim of this review is to focus on the multifaceted nature of microvascular impairment in diabetes through available evidence of specific consequences in often overlooked organs. A better understanding of diabetes microangiopathy in non-target organs provides a broader perspective on the systemic nature of the disease, underscoring the importance of recognising the comprehensive range of complications beyond the classic target sites.

Associations between spirometric measures and exercise capacity in type 2 diabetes

BACKGROUND

Physical exercise aids glycemic control and the prevention of diabetes-related complications. However, exercise beyond an individual's pulmonary functional capacity may be detrimental. To date, little is known about the relationship between pulmonary function and exercise capacity in people with type 2 diabetes (T2D). We investigated the relationship between pulmonary function and exercise capacity in T2D.

METHODS

Spirometry and 6-min walk test (6MWT) were conducted for 263 systematically sampled adults with T2D without primary heart/lung disease. The primary measure of exercise capacity was the 6-min walk distance (6MWD); impaired exercise capacity was defined as 6MWD<400 m. Logistic regression analyses were used to assess the associations between spirometric measures and exercise capacity with adjustments for age, sex, height, body mass index, diabetes duration, glycated hemoglobin concentration, smoking, suboptimum blood pressure control, and total cholesterol concentration.

RESULTS

Compared with individuals with normal spirometry, those with pulmonary restriction/obstruction had significantly lower 6MWD (404.67 m vs. 451.70),p < 0.001). The proportion of individuals with impaired exercise capacity was higher in individuals with impaired pulmonary function compared with those with normal pulmonary function (39.8% vs. 20.7%,p = 0.001). In the unadjusted models, decreasing Z-score FEV1 [odds ratio 1.40, 95% confidence interval (1.07-1.83),p = 0.013] and Z-score FVC [1.37 (1.06-1.76),0.016], but not Z-score FEV1/FVC ratio [1.00 (0.78-1.27),0.972] were significantly associated with impaired exercise capacity. In the fully adjusted model, the strength of association remained statistically significant for Z-score FEV1 [1.60 (1.06-2.41),0.025] but not Z-score FVC [1.48 (0.98-2.23),0.065].

CONCLUSIONS

Our study shows inverse associations between FEV1 and impaired exercise capacity in T2D, Future research could characterize optimal exercise levels based on a patient's FEV1.

Spirometric Lung Functions in Type 2 Diabetes Mellitus: A Hospital-Based Study

Objective This cross-sectional case-control study was conducted with the aim to analyze spirometric lung functions in type 2 diabetes mellitus (T2DM) patients and to correlate the spirometric dysfunction with (a) duration of diabetes, b) metabolic control of diabetes, and c) microvascular complications of diabetes. Methods Pulmonary function tests (PFTs) were performed in 50 T2DM patients and 50 normal healthy controls aged <80 years by using an electronic spirometer. The PFTs recorded were as follows: forced vital capacity (FVC), forced expiratory volume in one second (FEV1), FEV1%, forced expiratory flow 25 (FEF25), forced expiratory flow 25-75 (FEF25-75), and peak expiratory flow rate (PEFR). The glycated hemoglobin (HbA1c) of all the patients was measured by affinity chromatography using the NycoCard HbA1C kit. The assessment of diabetic microvascular complications was performed as follows: peripheral neuropathy was done using Michigan Neuropathy Screening Instrument (MNSI), diabetic retinopathy using fundus examination, and diabetic nephropathy using solid phase/sandwich-format/immunometric assay using NycoCard U-albumin kit. PFTs of diabetic patients and controls were compared by applying an independent sample t-test. The correlation between FVC and FEV1, and HbA1c and duration of illness in diabetic patients was analyzed by applying the Pearson coefficient. Results  The cases had low FVC (103.82 ±24.43 vs. 116.08 ±13.66), FEV1 (101.36 ±24.23 vs. 110.26 ±14.39), FEV1% (97.56 ±8.64 vs. 103.84 ±5.06), PEFR (101.52 ±27.18 vs. 116.96 ±14.96), and FEF 25-75 (73.56 ±29.19 vs. 98.40 ±14.45) compared to controls, and the difference was statistically significant. A significant negative correlation was found between spirometry parameters and duration of illness as well as HbA1c. Spirometric lung dysfunction also negatively correlated with microvascular complications of diabetes. Among various microvascular complications, retinopathy correlated best with various spirometric parameters. Conclusion Based on our findings, T2DM patients had a significant decrease in their spirometric indices. The pattern of spirometric dysfunction was suggestive of "mixed ventilatory dysfunction". The study results highlight the need to include PFTs in the periodic check-up as part of the comprehensive management of diabetic patients. Hence, pulmonary function should be included in the periodic comprehensive diabetic check for the holistic management of these patients.

Diabetic endothelial microangiopathy and pulmonary dysfunction

Type 2 diabetes mellitus (T2DM) is a widespread metabolic condition with a high global morbidity and mortality rate that affects the whole body. Their primary consequences are mostly caused by the macrovascular and microvascular bed degradation brought on by metabolic, hemodynamic, and inflammatory variables. However, research in recent years has expanded the target organ in T2DM to include the lung. Inflammatory lung diseases also impose a severe financial burden on global healthcare. T2DM has long been recognized as a significant comorbidity that influences the course of various respiratory disorders and their disease progress. The pathogenesis of the glycemic metabolic problem and endothelial microangiopathy of the respiratory disorders have garnered more attention lately, indicating that the two ailments have a shared history. This review aims to outline the connection between T2DM related endothelial cell dysfunction and concomitant respiratory diseases, including Coronavirus disease 2019 (COVID-19), asthma, chronic obstructive pulmonary disease (COPD) and idiopathic pulmonary fibrosis (IPF).

Association of Pulmonary Function Decline over Time with Longitudinal Change of Glycated Hemoglobin in Participants without Diabetes Mellitus

Pulmonary damage and function impairment were frequently noted in patients with diabetes mellitus (DM). However, the relationship between lung function and glycemic status in non-DM subjects was not well-known. Here, we evaluated the association of longitudinal changes of lung function parameters with longitudinal changes of glycated hemoglobin (HbA1c) in non-DM participants. The study enrolled participants without prior type 2 DM, hypertension, and chronic obstructive pulmonary disease (COPD) from the Taiwan Biobank database. Laboratory profiles and pulmonary function parameters, including forced vital capacity (FVC) and forced expiratory volume in 1 s (FEV1), were examined at baseline and follow-up. Finally, 7055 participants were selected in this study. During a mean 3.9-year follow-up, FVC and FEV1 were significantly decreased over time (both p < 0.001). In the multivariable analysis, the baseline (unstandardized coefficient β = −0.032, p < 0.001) and longitudinal change (unstandardized coefficient β = −0.025, p = 0.026) of FVC were negatively associated with the baseline and longitudinal change of HbA1c, respectively. Additionally, the longitudinal change of FVC was negatively associated with the risk of newly diagnosed type 2 DM (p = 0.018). During a mean 3.9-year follow-up, our present study, including participants without type 2 DM, hypertension, and COPD, demonstrated that the baseline and longitudinal change of FVC were negatively and respectively correlated with the baseline and longitudinal change of HbA1c. Furthermore, compared to those without new-onset DM, participants with new-onset DM had a more pronounced decline of FVC over time.

Effect of Glycated Hemoglobin (HbA1c) and Duration of Disease on Lung Functions in Type 2 Diabetic Patients

Diabetes mellitus is a highly challenging global health care problem. This study aimed to assess the effect of glycated hemoglobin (HbA1c) and duration of diabetes on lung function in type 2 diabetic patients and assess whether duration or high HbA1c is more noxious to damage the lung functions. A total of 202 participants, 101 patients with type 2 diabetes mellitus (T2DM), and 101 age-, gender-, height-, and weight-matched controlled subjects were recruited. The HbA1c was measured through a clover analyzer, and lung function test parameters were recorded by spirometry. The results revealed a significant inverse correlation between HbA1c and Vital Capacity (VC) (r = -0.221, p = 0.026), Forced Vital Capacity (FVC) (r = -0.261, p = 0.008), Forced Expiratory Volume in First Second (FEV1) (r = -0.272, p = 0.006), Forced Expiratory Flow 25% (FEF-25%) (r = -0.196, p = 0.050), Forced Expiratory Flow 50% (FEF-50%) (r = -0.223, p = 0.025), and Forced Expiratory Flow 75% (FEF-75%) (r = -0.169, p = 0.016). Moreover, FEV1 (p = 0.029), FEV1/FVC% (p = 0.006), FEF-50% (p = 0.001), and FEF-75% (p = 0.003) were significantly lower in the diabetic group with duration of disease 5-10 and >10 years compared to the control group. The overall results concluded that high HbA1c or uncontrolled diabetes mellitus has a more damaging effect on lung function impairment compared to the duration of diabetes mellitus. Physicians must regularly monitor the HbA1c level while treating diabetic patients, as good glycemic control is essential to minimize the complications of DM, including lung function impairment in patients with T2DM.