Metabolic Syndrome/Insulin Resistance Syndrome/Pre-Diabetes ORIGINAL ARTICLE Vital Capacity as a Predictor of Incident Type 2 Diabetes The Atherosclerosis Risk in Communities study 1 3 HSIN-CHIEH YEH, PHD JAMES S. PANKOW, PHD studies (11–14) have consistently shown 1,2 4 NARESH M. PUNJABI, MD, PHD BRUCE B. DUNCAN, MD, PHD that adults with diabetes have lower vital 2 1,2 NAE-YUH WANG, PHD FREDERICK L. BRANCATI, MD, MHS capacity than their nondiabetic counter- parts, but such studies cannot establish temporal sequence. Prospective studies have tentatively identified lower vital ca- pacity as a predictor of hyperinsulinemia OBJECTIVE — To test the hypothesis that lower vital capacity is cross-sectionally associated (3) and type 2 diabetes (4,5,25) but have with features of insulin resistance and is an independent predictor of incident type 2 diabetes. had limitations related to sample size and availability of diabetes-related data. We RESEARCH DESIGN AND METHODS — We conducted a prospective cohort study of vital capacity as a predictor of incident type 2 diabetes using 9-year follow-up data on 11,479 therefore analyzed longitudinal data from middle-aged adults without diabetes at baseline from the Atherosclerosis Risk in Communities the Atherosclerosis Risk in Communities (ARIC) Study. (ARIC) study, a biracial community- based study of 15,792 middle-aged RESULTS — Forced vital capacity (FVC) and forced expiratory volume in 1 s were measured adults, to test the hypothesis that lower at baseline using standard spirometry. Incident type 2 diabetes cases were ascertained during lung function, as indicated by lower vital follow-up. At baseline, low FVC (% predicted) was independently associated with indicators of capacity, is cross-sectionally associated the insulin resistance syndrome, including higher fasting levels of glucose, insulin, and triglyc- with features of insulin resistance and is erides; lower fasting HDL cholesterol; and higher systolic blood pressure. In prospective analy- an independent predictor of incident type ses, there were graded associations between low FVC (% predicted) and incidence of type 2 2 diabetes. diabetes in men and women. These associations persisted in multivariable analyses that adjusted for age, race, adiposity, smoking, physical activity, and ARIC center. Compared with individuals in the highest quartile of FVC (% predicted), the fully adjusted hazard ratio (95% CI) of diabetes RESEARCH DESIGN AND in individuals in the lowest quartile was 1.6 (1.3–2.0) in men and 1.7 (1.3–2.1) in women. These METHODS relationships were stronger in those who have never smoked. — The ARIC study is an on-going, prospective cohort study de- CONCLUSIONS — Lower vital capacity is an independent predictor of incident type 2 signed to assess subclinical and clinical diabetes. Pulmonary factors related to vital capacity deserve attention as possible risk factors for atherosclerosis in a cohort of adults aged insulin resistance and diabetes. 45–64 years, selected using probability sampling from the following four U.S. Diabetes Care 28:1472–1479, 2005 communities: Forsyth County, NC; Jack- son, MS; the northwest suburbs of Min- neapolis, MN; and Washington County, mpaired lung function has attracted effects of hypoxemia on glucose and insu- MD. By design, the Jackson site exclu- growing interest as a potentially novel lin regulation (2,6), lung-related inflam- sively recruited African Americans, I risk factor for glucose intolerance matory mediators and their effects on thereby accounting for 90% of African (1,2), insulin resistance (3), and type 2 insulin signaling (1,7,8), and adverse ear- Americans in the study. Most of the re- diabetes (4,5,25). Possible mechanisms ly-life exposures and their effects on or- maining African Americans came from for the hypothesized link include direct gan development (9,10). Cross-sectional the Forsyth County cohort. The sampling ●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●● procedure and methods used in the ARIC 1 2 study have been previously described From the Department of Epidemiology, Johns Hopkins University, Baltimore, Maryland; the Department (15). The current study was based on of Medicine, Johns Hopkins University, Baltimore, Maryland; the 3Division of Epidemiology, University of Minnesota, Minneapolis, Minnesota; and the 4Social Medicine Department, Federal University of Rio Grande 9-year follow-up data that included a do Sul, Porto Alegre, Brazil. baseline visit from 1987 through 1989 Address correspondence and reprint requests to Dr. Frederick L. Brancati, The Welch Center for Preven- and three follow-up clinic visits sched- tion, Epidemiology, and Clinical Research, Johns Hopkins Medical Institutions, 2024 E. Monument St., Suite uled 3 years apart. Of participants still 2-600, Baltimore, MD 21205. E-mail: [email protected]. Received for publication 7 October 2004 and accepted in revised form 16 March 2005. alive at the time of the scheduled visits, Abbreviations: ARIC, Atherosclerosis Risk in Communities; DBP, diastolic blood pressure; FEV1, forced response rates for the second, third, and expiratory volume in 1 s; FVC, forced vital capacity; SBP, systolic blood pressure. fourth follow-ups were 93, 86, and 81%, A table elsewhere in this issue shows conventional and Syste`me International (SI) units and conversion respectively. factors for many substances. For the current analysis, individuals © 2005 by the American Diabetes Association. The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby were excluded based on the following cri- marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact. teria: ethnicity other than black or white 1472 DIABETES CARE, VOLUME 28, NUMBER 6, JUNE 2005 Yeh and Associates Table 1—Baseline characteristics of men and women according to FVC (% predicted) quartile FVC (% predicted) quartile* I (low) (Ͻ 90.8) II (90.9–99.4) III (99.5–108.4) IV (high) (Ͼ108.4) P for trend† Men n 1,283 1,281 1,281 1,282 African American 26 19 16 14 Ͻ0.0001 Age at baseline (years) 55 Ϯ 5.6 54 Ϯ 5.7 54 Ϯ 5.6 53 Ϯ 5.7 Ͻ0.0001 Education Ͻ12 years 26 20 20 15 Ͻ0.0001 Parental history of diabetes 12 13 12 10 0.11 Smoking status Current 36 27 22 18 Ͻ0.0001 Former 42 45 46 45 — Never 22 28 32 37 — Pack-years‡ 36 Ϯ 22.9 31 Ϯ 23.8 28 Ϯ 20.3 24 Ϯ 18.4 Ͻ0.0001 Sport index 2.4 Ϯ 0.8 2.6 Ϯ 0.8 2.7 Ϯ 0.8 2.8 Ϯ 0.8 Ͻ0.0001 BMI (kg/m2) 28.1 Ϯ 4.6 27.5 Ϯ 4.1 26.9 Ϯ 3.6 26.6 Ϯ 3.3 Ͻ0.0001 Waist-to-hip ratio 0.96 Ϯ 0.06 0.96 Ϯ 0.05 0.96 Ϯ 0.05 0.94 Ϯ 0.05 Ͻ0.0001 Height (cm) 176 Ϯ 6.5 176 Ϯ 6.5 176 Ϯ 6.7 177 Ϯ 6.6 0.06 Waist (cm) 101 Ϯ 11.7 99 Ϯ 10.4 97 Ϯ 9.8 96 Ϯ 9.1 Ͻ0.0001 Metabolic syndrome§ 36 26 22 15 Ͻ0.0001 Fibrinogen (g/l) 3.1 Ϯ 0.7 3.0 Ϯ 0.6 2.9 Ϯ 0.6 2.8 Ϯ 0.6 Ͻ0.0001 White blood cell count (ϫ109/l) 6.4 Ϯ 1.9 6.2 Ϯ 1.8 6.1 Ϯ 2.6 5.9 Ϯ 1.7 Ͻ0.0001 FVC (l) 3.8 Ϯ 0.5 4.4 Ϯ 0.5 4.8 Ϯ 0.5 5.5 Ϯ 0.6 Ͻ0.0001 Ϯ Ϯ Ϯ Ϯ Ͻ FEV1 (l) 2.7 0.5 3.3 0.5 3.6 0.5 4.0 0.6 0.0001 Ϯ Ϯ Ϯ Ϯ FEV1/FVC 72.9 9.3 74.3 7.4 74.2 6.8 73.6 6.4 0.05 I (low) (Ͻ 95.7) II (95.8–105.3) III (105.4–114.6) IV (high) (Ͼ114.6) P for trend† Women n 1,588 1,588 1,588 1,588 African American 33 26 21 20 Ͻ0.0001 Age at baseline (years) 54 Ϯ 5.8 53 Ϯ 5.6 53 Ϯ 5.6 54 Ϯ 5.6 0.06 Education Ͻ12 years 26 19 17 15 Ͻ0.0001 Parental history of diabetes 12 13 14 13 0.71 Smoking status Current 34 22 19 15 Ͻ0.0001 Former 18 22 24 25 — Never 48 56 57 60 — Pack-years‡ 25.0 Ϯ 17.8 20.6 Ϯ 17.3 17.6 Ϯ 15.8 17.3 Ϯ 15.6 Ͻ0.0001 Sport index 2.2 Ϯ 0.7 2.3 Ϯ 0.7 2.4 Ϯ 0.8 2.5 Ϯ 0.8 Ͻ0.0001 BMI (kg/m2) 28.7 Ϯ 6.6 27.3 Ϯ 5.8 26.5 Ϯ 5.1 26.1 Ϯ 4.7 Ͻ0.0001 Waist-to-hip ratio 0.91 Ϯ 0.08 0.89 Ϯ 0.08 0.87 Ϯ 0.08 0.87 Ϯ 0.08 Ͻ0.0001 Height (cm) 163 Ϯ 5.8 163 Ϯ 5.9 162 Ϯ 6.0 162 Ϯ 6.1 Ͻ0.0001 Waist (cm) 98 Ϯ 16.3 94 Ϯ 14.9 91 Ϯ 13.4 90 Ϯ 12.8 Ͻ0.0001 Metabolic syndrome§ 35 27 21 16 Ͻ0.0001 Fibrinogen (g/l) 3.2 Ϯ 0.7 3.0 Ϯ 0.6 2.9 Ϯ 0.5 2.9 Ϯ 0.6 Ͻ0.0001 WBC count (ϫ109/l) 6.3 Ϯ 1.9 5.9 Ϯ 1.9 5.7 Ϯ 1.6 5.5 Ϯ 1.6 Ͻ0.0001 FVC (l) 2.7 Ϯ 0.4 3.2 Ϯ 0.4 3.5 Ϯ 0.4 3.8 Ϯ 0.5 Ͻ0.0001 Ϯ Ϯ Ϯ Ϯ Ͻ FEV1 (l) 2.0 0.4 2.4 0.3 2.6 0.3 2.9 0.4 0.0001 Ϯ Ϯ Ϯ Ϯ FEV1/FVC 76.0 8.2 76.6 6.1 76.2 5.6 75.1 5.8 0.46 Data are mean Ϯ SD or percent.