Restrictive Lung Disease Linked to Incident Type 2 Diabetes

"The association between impaired lung function and cardiovascular disease (CVD) morbidity and mortality is well established, although the mechanisms remain unclear," write S. Goya Wannamethee, PhD, from University College Medical School in London, and colleagues. 

"Reduced lung function is also one of the many clinical features associated with Type 2 diabetes mellitus (T2DM). Diabetes has been shown to be associated with impaired pulmonary function in a restrictive pattern and prospective studies have suggested that reduced lung function may be associated with the development of T2DM." 

The goals of the study were to prospectively evaluate the associations between lung function and the risk for Type 2 diabetes and fatal and non-fatal CHD and to test the hypothesis that inflammation may be the mechanism explaining these associations. At general practices in 24 British towns, 4,434 men aged 40 to 59 years with no history of cardiovascular disease (CHD or stroke) or diabetes were recruited and were followed up for 20 years. 

During follow-up, there were 680 major CHD events, of which 276 were fatal, and 256 incident cases of Type 2 diabetes. After adjustment for age, potential confounding variables and metabolic risk factors, forced vital capacity (FVC) and forced expiratory volume in 1 second (FEV₁), but not FEV₁/FVC ratio, were significantly and inversely associated with incident events of Type 2 diabetes and fatal CHD, but not nonfatal CHD. 

There was a significant inverse association between lung function and C-reactive protein (CRP) as well as interleukin 6 (IL-6). After further adjustment for these factors, the inverse associations with Type 2 diabetes for FVC and FEV₁ were no longer statistically significant (P = .14 and P = .11 for trend). However, the inverse associations with Type 2 diabetes remained significant for fatal CHD (P = .03 and P = .01, respectively). 

"Restrictive rather than obstructive impairment of lung function is associated with incident T2DM (and fatal CHD) with both associations partially explained by traditional and metabolic risk factors and inflammation," the study authors write. 

"The association between reduced lung function and fatal CHD and T2DM in particular was to some extent associated with inflammatory pathways," the study authors conclude. "Further studies are now needed to extend such novel observations. The association between reduced lung function and development of T2DM and fatal CHD events may provide another possible explanation for the increased risk of fatal CHD in individuals with T2DM."

Diabetes Care, June 2, 2010