Reduced lung volumes and airflow are a complication of type 2 diabetes.
"Several cross-sectional studies have shown that type 2 diabetes is associated with reduced lung function," write Wendy A. Davis, MPH, from the University of Western Australia and Fremantle Hospital. "This may mean that diabetes and impaired lung function share common pathophysiologic determinants rather than the lung being a target organ in diabetes."
From a community-based cohort, 495 patients of European origin with type 2 diabetes and no history of pulmonary disease had baseline spirometry between 1993 and 1994. Repeat spirometry was performed in 125 patients at a mean follow-up of 7.0 years, and outcome measures were corrected for body temperature, air pressure, and water saturation.
At baseline, the mean percentage-predicted values of forced vital capacity (FVC), forced expiratory volume in one second (FEV1), vital capacity (VC), and peak expiratory flow (PEF) were decreased more than 10% in the overall cohort. In the 125 prospectively studied patients, mean FVC declined at 68 mL/year, FEV1 at 71 mL/year, VC at 84 mL/yr, and PEF at 17 L/min/year.
Higher updated mean HbA1c, follow-up HbA1c, or follow-up fasting plasma glucose reflecting poor glycemic control predicted declining lung function measures. Cox proportional hazards analysis revealed that decreased FEV1 percentage-predicted value was an independent predictor of all-cause mortality.
Study limitations include selection of healthy survivors for the prospective study, use of two different spirometers at baseline and at follow-up, and possible effects of chronic illness on effort-dependent measures. However, duration of diabetes was not consistently associated with changes in lung function.
", the severity of which relates to glycemic exposure," the authors write. "Our data support the suggestion that The Raine Foundation of the University of Western Australia funded the Fremantle Diabetes Study. The senior author is a member of the AERx (inhaled insulin) Advisory Board for Novo Nordisk Pharmaceuticals.
In an accompanying editorial, David A. Kaminsky, from the University of Vermont in Burlington, puts these findings in the context of other research demonstrating that lung function is an independent risk factor of cardiovascular, pulmonary, and all-cause mortality.
"If a low FEV1 is a marker of diabetes or poor glycemic control, then efforts should be focused on identifying and modifying known risk factors for cardiopulmonary disease and diabetes," Dr. Kaminsky writes. "If a low FEV1 reflects a causative role played by the lungs in the development of diabetes, then optimizing lung health through smoking cessation, avoidance of irritant and toxic exposures, control of underlying airway inflammation, and promotion of physical activity seems warranted. Indeed, it's time to add the spirometer to the tools available for monitoring diabetes and its important sequel