Relationship between pulmonary function and elevated glycated hemoglobin levels in health checkups: A cross-sectional observational study in Japanese participants

BACKGROUND: Insulin resistance has been associated with cytokines, including interleukin-6 and tumor necrosis factor alpha soluble receptor, both of which are elevated in chronic obstructive pulmonary disease (COPD). Few studies have investigated the relationship between pulmonary function tests using spirometry (PFT) and fasting plasma glucose (FPG) or glycated hemoglobin (HbA(1c)) levels in Japanese participants. The purpose of this study was to clarify the relationship between PFT in Japanese people who had health checkups and their FPG or HbA(1c) levels. In the context of preventative medicine, we intend to connect early detection of COPD to an index of blood sugar. METHODS: From August 2013 through March 2014, 1019 participants underwent health checkups. PFT, FPG, and HbA(1c) measurements were conducted. HbA(1c) levels were measured according to National Glycohemoglobin Standardization Program guidelines. RESULTS: Participants with FPG ≥100 mg/dL and HbA(1c) ≥5.6% showed a significantly lower forced expiratory volume in 1 s:forced vital capacity ratio (FEV(1)/FVC) compared to participants with lower FPG and Hb1Ac levels. Prevalence of FEV(1)/FVC values <70% in PFT differed significantly depending on sex, age, body mass index, FPG, HbA(1c), and smoking habits. Age (≥60 years), HbA(1c) (≥5.6%), and current or former smoking were associated with FEV(1)/FVC values <70%. CONCLUSION: In Japan, HbA(1c) levels were higher in participants with FEV(1)/FVC values <70% in PFT than in those with FEV(1)/FVC ≥70%. In preventive medicine, PFT by spirometry should be performed in elderly participants with elevated HbA(1c) levels who are current or former smokers.