Association between lung capacity measurements and abnormal glucose metabolism : findings from the Crossroads study

Aim: To examine the association between lung function and metabolic syndrome/Type 2 diabetes. Methods: A total of 1454 adults from rural Victoria, Australia, from randomly selected households included in the Crossroads study, provided spirometric measurements including forced vital capacity, forced expiratory volume in 1 s, predicted percentage value of forced expiratory volume in 1 s and forced vital capacity predicted percentage value. Assessments also included HbA1c, metabolic syndrome components and a 75-g oral glucose tolerance test. The area under the receiver-operating characteristic curves for waist circumference were compared with those for combinations of waist circumference and raw spirometric measures (forced vital capacity and forced expiratory volume in 1 s) for identifying metabolic syndrome or Type 2 diabetes. Results: Participants with a greater number of metabolic syndrome components were more likely to have reduced lung function, particularly if Type 2 diabetes was present: the predicted value of forced expiratory volume in 1 s decreased by 5-6% for participants with 2-4 metabolic syndrome components, and by 9% for those with Type 2 diabetes. The risk of metabolic syndrome or Type 2 diabetes was inversely associated with higher spirometry values (forced expiratory volume in 1 s percentage predicted value: odds ratio for 2-4 metabolic syndrome components 0.36-0.21 in women and 0.32-0.30 men; the odds ratio for Type 2 diabetes was 0.36 in women and 0.28 in men). Receiver-operating characteristic curve analysis for identifying metabolic syndrome and Type 2 diabetes revealed significant differences between the area under the receiver-operating characteristic curve with waist circumference alone and that for the combination of waist circumference with lung capacity measures. Conclusion: Pulmonary function is lower in people with metabolic syndrome and Type 2 diabetes. Spirometry variables are independent predictors of metabolic syndrome and Type 2 diabetes.