Benefit of Metformin in COPD: An Effect on Autonomic Nervous System?

Relationship between diabetes and respiratory diseases-Clinical and therapeutic aspects

Diabetes is a common metabolic disorder affecting the entire body with high morbidity and mortality worldwide. The major complications related to diabetes are mostly due to the macrovascular and microvascular bed impairment due to metabolic, hemodynamic and inflammatory factors. However, studies over the past decades have added also the lung as a target organ in both type 1 and type 2 diabetes. Diabetes has always been addressed as a major comorbidity conditioning the disease behaviour and the natural history of several respiratory diseases. Increased interest has recently focused on the pathophysiology of the metabolic glycaemic disorder and the respiratory diseases suggesting a similar background shared by the two conditions. The true relationship between pulmonary diseases and diabetes mellitus has not been clarified, this review aims to summarize the link between diabetes and coexisting respiratory diseases such as asthma, chronic obstructive pulmonary disease, respiratory infections, cystic fibrosis, lung cancer and obstructive sleep apnea from a pathogenetic and therapeutic point of view.

Metformin and risk of chronic obstructive pulmonary disease in diabetes patients

PURPOSE

This study aimed to investigate whether metformin can affect risk of chronic obstructive pulmonary disease (COPD) in type 2 diabetes (T2D) patients.

METHODS

T2D patients newly diagnosed during 1999-2005 were enrolled from the reimbursement database of Taiwan's National Health Insurance system and followed up to 31 December 2011. Analyses were conducted in an unmatched cohort (92,272 ever-users and 10,697 never-users of metformin) and a propensity score (PS) matched pair cohort (10,697 ever-users and 10,697 never-users). Cox regression incorporated into the inverse probability of treatment weighting using the PS was used to estimate hazard ratios (HRs).

RESULTS

In the unmatched cohort, 2573 never-users and 13,840 ever-users developed COPD with respective incidences of 5994.64 and 3393.19 per 100,000 person-years. The overall HR was 0.560 (95% confidence interval [CI]: 0.537-0.584). HRs for the first (<25.27months), second (25.27-55.97months) and third (>55.97months) tertiles of cumulative duration were 1.021 (0.975-1.070), 0.575 (0.548-0.603) and 0.265 (0.252-0.280), respectively. Analyses of the matched cohort showed an overall HR of 0.643 (0.605-0.682), with HRs of 1.212 (1.122-1.309), 0.631 (0.578-0.689) and 0.305 (0.273-0.340) for the respective tertiles.

CONCLUSION

A reduced risk of COPD is observed in metformin users with T2D.

Pleiotropic effects of hypoglycemic agents: implications in asthma and COPD

Diabetes mellitus (DM) is a complex multifactorial disease due to the interaction between environmental noxae and genetic predisposition. Furthermore, an increased association between DM, especially Type 2 diabetes mellitus (T2DM), and the onset of pulmonary function impairment with a bronchial hyperresponsiveness has been documented. DM is a risk factor for accelerated decline in FEV₁ and the development of asthma and COPD. The increased blood glucose concentrations along with higher levels of oxidative stress and inflammation can influence the pulmonary function and, since hypoglycemic drugs can act on these different defects we can hypothesize their direct effect on obstructive pulmonary diseases. Metformin, a biguanide, is the molecule having several evidences of its action on asthma and COPD in patients with T2DM. In this population, Metformin can ameliorate pulmonary outcomes reducing high glucose concentrations, inflammation through the activation of the AMP-activated protein kinase, leading to the decreased production of pro-inflammatory cytokines and blunting allergic eosinophilic airway inflammation. There are evidences of Pioglitazone role on asthma, since the activation of PPARγ Pioglitazone might inhibit the synthesis and release of pro-inflammatory cytokines. Indeed, Pioglitazone can improve symptoms associated with asthma reducing episodes of exacerbation and oral steroid prescription. Finally, randomized clinical trials using hypoglycemic agents on patients with asthma and COPD with and without DM should be proposed as well as the implementation of a new formulation of hypoglycemic agents to make it possible to administer it via aerosol.