Lung function changes in older people with metabolic syndrome and diabetes

AIM: Restrictive lung dysfunction (RLD; defined as reduced forced vital capacity [FVC] in the presence of normal forced expiratory volume in 1 s [FEV1]/FVC ratio) is highly prevalent in the elderly, and is associated with diabetes, metabolic syndrome (MetS) and abdominal obesity. The aim of this study was to assess the relative contribution of diabetes, MetS and abdominal obesity in characterizing RLD in the elderly. METHODS: This was cross-sectional analysis of 192 consecutive, community-dwelling persons (mean age 70.8 ± 8 years). The participants were grouped according to the number of MetS components (i.e. 0, 1, 2, 3 or 4) and the presence of diabetes. According to the Adult Treatment Panel-III criteria, participants with three or four components were considered to be affected by MetS. Independent correlates of RLD and obstructive lung dysfunction (OLD; FEV1/FVC < 0.70) were assessed by logistic regression models. RESULTS: The mean age of the sample population was 70.8 years. FVC expressed as percent of the predicted value declined for an increasing number of MetS components (P < 0.0001), but diabetes did not account for further ventilatory decline. Consistently, MetS (OR 3.03, 95% CI 1.16-7.89) and abdominal obesity (OR 4.89, 95% CI 1.17-20.3), but not diabetes, were independently associated with RLD. OLD did not worsen for an increasing number of MetS components and was only related to age (OR 1.07, 95% CI 1.01-1.13) and smoking (OR 1.04, 95% CI 1.01-1.06). CONCLUSIONS: MetS and abdominal obesity, two conditions of prediabetes, but not diabetes itself, are closely associated with RLD. These conditions might be implicated in the pathogenesis of the RLD, which is frequently observed in diabetic patients.