title: Parathyroid hormone is associated with incident diabetes in white, but not black adults: The Atherosclerosis Risk in Communities (ARIC) Study.
abstract: OBJECTIVE
  Accumulating evidence has linked elevated parathyroid hormone (PTH) with insulin resistance, beta cell dysfunction and dysglycaemia, however, its role in the development of diabetes is largely unclear, particularly among non-whites. We sought to examine the association of PTH with the incidence of diabetes.
  
  
  METHODS
  We studied 8066 white and 2034 black adults aged 46-70 years at baseline (1990-92) from the ARIC Study with follow-up for incident diabetes ascertained during study visits conducted in 1993-95 and 1996-98. Hazard ratios (HR) and their 95% CIs for diabetes adjusted for demographics, lifestyle, and 25-hydroxyvitamin D were estimated according to PTH measured at baseline.
  
  
  RESULTS
  PTH was higher among blacks than whites (median [IQR], 43.8 [35.0-55.8] vs. 37.9 [30.4-47.3] pg/mL; P<0.001). During a median follow-up of 6 years, 498 white and 167 black participants developed diabetes. The association of PTH with diabetes varied significantly by race (P-interaction 0.02). PTH was not associated with risk for diabetes among black adults. Among whites, HRs according to quintiles of PTH were 1 (referent), 0.95 (0.71, 1.29), 0.95 (0.70, 1.28), 1.12 (0.84, 1.51), and 1.31 (0.98, 1.76) (P-trend 0.03). When a clinical cut-point for PTH was applied (≥65pg/mL; 5.7% of whites), the HR for diabetes among whites was 1.38 (1.01, 1.88). Results were similar when restricted to participants with normal baseline kidney function.
  
  
  CONCLUSIONS
  In this large, population-based study, elevated PTH was independently associated with risk for diabetes among white, but not black adults. Further studies are needed to elucidate the mechanisms that may underlie this differential association of PTH with diabetes across race groups.
authors.affiliation: Division of Cardiovascular Sciences, National Heart, Lung, and Blood Institute, Bethesda, MD, United States. Electronic address: reisjp@mail.nih.gov.
authors.forename: J P
authors.initials: JP
authors.lastname: Reis
authors.affiliation: Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, United States.
authors.forename: E
authors.initials: E
authors.lastname: Selvin
authors.affiliation: Division of Epidemiology and Community Health, University of Minnesota, Minneapolis, MN, United States.
authors.forename: J S
authors.initials: JS
authors.lastname: Pankow
authors.affiliation: Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, United States; Division of Cardiology, Johns Hopkins School of Medicine, Baltimore, MD, United States.
authors.forename: E D
authors.initials: ED
authors.lastname: Michos
authors.affiliation: Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, United States.
authors.forename: C M
authors.initials: CM
authors.lastname: Rebholz
authors.affiliation: Division of Epidemiology and Community Health, University of Minnesota, Minneapolis, MN, United States.
authors.forename: P L
authors.initials: PL
authors.lastname: Lutsey
mesh_terms: D000328:Adult; D001741:Black or African American / Q000706:statistics & numerical data*; D000368:Aged; D050197:Atherosclerosis / Q000453:epidemiology; D003920:Diabetes Mellitus / Q000097:blood* / Q000208:ethnology*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D010281:Parathyroid Hormone / Q000097:blood*; D012111:Residence Characteristics; D012307:Risk Factors; D044465:White People / Q000706:statistics & numerical data*
chemical_list: D010281:Parathyroid Hormone
keywords: Diabetes; Parathyroid hormone; Prospective study; Race