title: Urban-rural differences explain the association between serum 25-hydroxyvitamin D level and insulin resistance in Korea.
abstract: An increasing number of studies report associations between low serum 25-hydroxyvitamin D [25(OH)D] level and insulin resistance; however, whether low vitamin D levels directly contribute to increased insulin resistance is unclear. We investigated the impact of residential area on the association between 25(OH)D and insulin resistance in elderly Koreans. Using data from the Korean Urban Rural Elderly study, we conducted cross-sectional analyses in 1628 participants (505 men and 1123 women). Serum 25(OH)D was analyzed as both continuous and categorized variables. Homeostasis model assessment for insulin resistance (HOMA-IR) was calculated using fasting blood glucose and insulin levels. In men, 25(OH)D level was inversely associated with HOMA-IR (standardized β = -0.133, p < 0.001) after adjustment for age, body mass index, waist circumference, smoking, alcohol intake, exercise, and study year. However, we noted significant urban-rural differences in 25(OH)D level (43.4 versus 65.6 nmol/L; p < 0.001) and HOMA-IR (1.2 versus 0.8 mmol · pmol/L2; p < 0.001). When we additionally adjusted for residential area, the association between 25(OH)D and HOMA-IR was attenuated (standardized β = -0.063, p = 0.115). In women, the association between 25(OH)D and HOMA-IR was not significant before or after adjustment for residential area. Environmental or lifestyle differences in urban and rural areas may largely explain the inverse association between serum 25(OH)D and insulin resistance.
authors.affiliation: Department of Public Health, Yonsei University Graduate School, Seoul 120-752, Korea. sbm1396@yuhs.ac.
authors.forename: Bo Mi
authors.initials: BM
authors.lastname: Song
authors.affiliation: Department of Internal Medicine, Yonsei University College of Medicine, Seoul 120-752, Korea. yumie@yuhs.ac.
authors.forename: Yumie
authors.initials: Y
authors.lastname: Rhee
authors.affiliation: Department of Internal Medicine, Yonsei University College of Medicine, Seoul 120-752, Korea. cokim@yuhs.ac.
authors.forename: Chang Oh
authors.initials: CO
authors.lastname: Kim
authors.affiliation: Department of Sociology, Yonsei University College of Social Sciences, Seoul 120-752, Korea. yoosik@yonsei.ac.kr.
authors.forename: Yoosik
authors.initials: Y
authors.lastname: Youm
authors.affiliation: Department of Internal Medicine, Seoul National University Bundang Hospital, Seongnam 463-707, Korea. kyoungmin02@gmail.com.
authors.forename: Kyoung Min
authors.initials: KM
authors.lastname: Kim
authors.affiliation: Department of Internal Medicine, Yonsei University College of Medicine, Seoul 120-752, Korea. leyme@yuhs.ac.
authors.forename: Eun Young
authors.initials: EY
authors.lastname: Lee
authors.affiliation: Cardiovascular and Metabolic Disease Etiology Research Center, Yonsei University College of Medicine, Seoul 120-752, Korea. jmlee01@yuhs.ac.
authors.forename: Ju-Mi
authors.initials: JM
authors.lastname: Lee
authors.affiliation: Cardiovascular and Metabolic Disease Etiology Research Center, Yonsei University College of Medicine, Seoul 120-752, Korea. yun3416@yuhs.ac.
authors.forename: Young Mi
authors.initials: YM
authors.lastname: Yoon
authors.affiliation: Cardiovascular and Metabolic Disease Etiology Research Center, Yonsei University College of Medicine, Seoul 120-752, Korea. hckim@yuhs.ac.
authors.forename: Hyeon Chang
authors.initials: HC
authors.lastname: Kim
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D044466:Asian People; D001786:Blood Glucose; D015992:Body Mass Index; D001835:Body Weight; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007328:Insulin / Q000097:blood; D007333:Insulin Resistance; D016014:Linear Models; D008297:Male; D056910:Republic of Korea; D012424:Rural Population; D011795:Surveys and Questionnaires; D014505:Urban Population; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood; D055105:Waist Circumference
chemical_list: D001786:Blood Glucose; D007328:Insulin; D014807:Vitamin D; C104450:25-hydroxyvitamin D