title: Rheumatoid factor mediates excess serum lipoprotein(a) for independent association with type 2 diabetes in men.
abstract: OBJECTIVE
  The potential association of rheumatoid factor (RF) and lipoprotein (Lp)(a) levels, as well as with the likelihood of type 2 diabetes and hypertension, needs exploring.
  
  
  METHODS
  Cross-sectional associations were sought in this unselected and population-based 1539-adult cohort (age 58.8±10.6 years). RF was assayed nephelometrically. Multiple logistic regression analyses were used for covariates of RF positivity and for the latter's association with diabetes and hypertension.
  
  
  RESULTS
  RF-positive individuals were older, fewer current smokers, had significantly lower fasting triglycerides (by 13%), higher fibrinogen, and tended to higher sex hormone-binding globulin (SHBG) levels. Whereas, women had a similar risk profile irrespective of RF status, RF-positive men had significantly higher Lp(a). In contrast to Lp(a) being positively correlated with SHBG in RF-negative subjects (r=0.08; p=0.007), an inverse correlation existed in seropositive individuals (r=-0.32, p=0.011), suggesting the interplay of an immune complex. In regression analyses, RF positivity was associated with Lp(a) in men but not in women, [OR 1.53 (1.19; 1.96)], independent of age, SHBG, and C-reactive protein (CRP). RF positivity was further associated with diabetes [OR 1.98 (95% CI 1.11; 3.52)] in the whole sample, additively to waist circumference and CRP, major determinants of diabetes. RF-positive subjects were not significantly associated independently with hypertension.
  
  
  CONCLUSIONS
  Autoimmune activation linked to Lp(a) is mediated by the autoantibody RF in contributing to the development of type 2 diabetes.
authors.affiliation: Department of Cardiology, Cerrahpaşa Faculty of Medicine, İstanbul University; İstanbul-Turkey. alt_onat@yahoo.com.tr.
authors.forename: Altan
authors.initials: A
authors.lastname: Onat
authors.forename: Evin
authors.initials: E
authors.lastname: Ademoğlu
authors.forename: Günay
authors.initials: G
authors.lastname: Can
authors.forename: Servet
authors.initials: S
authors.lastname: Altay
authors.forename: Ahmet
authors.initials: A
authors.lastname: Karagöz
authors.forename: Bayram
authors.initials: B
authors.lastname: Köroğlu
authors.forename: Hüsniye
authors.initials: H
authors.lastname: Yüksel
mesh_terms: D000328:Adult; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D003924:Diabetes Mellitus, Type 2 / Q000097:blood / Q000453:epidemiology*; D005260:Female; D006801:Humans; D006973:Hypertension / Q000097:blood / Q000453:epidemiology*; D017270:Lipoprotein(a) / Q000097:blood*; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D012217:Rheumatoid Factor / Q000097:blood*; D012737:Sex Factors; D012738:Sex Hormone-Binding Globulin / Q000378:metabolism; D014280:Triglycerides / Q000097:blood; D014421:Turkey / Q000453:epidemiology
chemical_list: D017270:Lipoprotein(a); D012738:Sex Hormone-Binding Globulin; D014280:Triglycerides; D012217:Rheumatoid Factor