Association between glycemic state and pulmonary function and effect of walking as a protective factor in subjects with diabetes mellitus

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.

Pathogenesis of diabetic complications: Exploring hypoxic niche formation and HIF-1α activation

Hypoxia is a common feature of diabetic tissues, which highly correlates to the progression of diabetes. The formation of hypoxic context is induced by disrupted oxygen homeostasis that is predominantly driven by vascular remodeling in diabetes. While different types of vascular impairments have been reported, the specific features and underlying mechanisms are yet to be fully understood. Under hypoxic condition, cells upregulate hypoxia-inducible factor-1α (HIF-1α), an oxygen sensor that coordinates oxygen concentration and cell metabolism under hypoxic conditions. However, diabetic context exploits this machinery for pathogenic functions. Although HIF-1α protects cells from diabetic insult in multiple tissues, it also jeopardizes cell function in the retina. To gain a deeper understanding of hypoxia in diabetic complications, we focus on the formation of tissue hypoxia and the outcomes of HIF-1α dysregulation under diabetic context. Hopefully, this review can provide a better understanding on hypoxia biology in diabetes.

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.