title: Low density lipoprotein cholesterol, lipoprotein(a), and apo(a) isoforms in the elderly: relationship to fasting insulin. Associazione Medica Sabin.
abstract: OBJECTIVE
  Insulin resistance/hyperinsulinemia are often associated with aging and could play an important role in the development of glucose intolerance and dyslipidemia in the elderly. We investigated the relationship between plasma fasting insulin with total cholesterol (TC) and low density lipoprotein LDL cholesterol (LDL-C), triglycerides (TG), lipoprotein(a) [Lp(a)] levels apolipoprotein (a) [apo (a)] isoforms in 100 free-living "healthy" octo-nonagenarians.
  
  
  RESULTS
  Fasting insulin was positively correlated with TG, whereas a negative relation was found with TC and LDL-C (r = -0.29 and r = -0.28 respectively; p < 0.01), LDL-C/apo B, HDL-C and apo A-I levels. Fasting insulin was also inversely correlated with Lp(a) levels (r = -0.22; p < 0.03), whereas the latter were significantly related with TC and LDL-C (r = 0.30 and r = 0.31; p < 0.005), TG (r = 0.21; p < 0.05) and apo B (r = 0.26; p < 0.02). There was a negative relation between Lp(a) levels and apo(a) isoforms: the greater the apo(a) molecular weight, the lower the Lp(a) level (p < 0.0001). Fasting insulin increased with apo(a) size, though the difference in insulin levels among apo(a) isoforms was not significant (p = 0.4). Multiple regression analysis showed that fasting insulin was the best predictor of LDL-C (R2 = 0.14; p = 0.002) irrespective of age, gender, BMI, waist circumference and TG, while apo(a) isoform size, BMI and waist circumference were related with Lp(a) irrespective of TC and LDL-C, TG and apo B (R2 = 0.35 to 0.37; p < 0.0001).
  
  
  CONCLUSIONS
  These results suggest that fasting insulin levels significantly influence LDL-C metabolism in old age. Lp(a) levels seem to be very strongly related to genetic background, although an indirect relation with insulin through adiposity and/or other associated lipid abnormalities cannot be ruled out.
authors.affiliation: 2nd Department of Internal Medicine, University of Ferrara School of Medicine, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Carantoni
authors.forename: G
authors.initials: G
authors.lastname: Zuliani
authors.forename: G
authors.initials: G
authors.lastname: Bader
authors.forename: E
authors.initials: E
authors.lastname: Palmieri
authors.forename: S
authors.initials: S
authors.lastname: Volpato
authors.forename: A
authors.initials: A
authors.lastname: Passaro
authors.forename: T
authors.initials: T
authors.lastname: Imbastaro
authors.forename: A
authors.initials: A
authors.lastname: Mezzetti
authors.forename: R
authors.initials: R
authors.lastname: Fellin
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000704:Analysis of Variance; D001054:Apolipoproteins A / Q000097:blood*; D001824:Body Constitution; D002784:Cholesterol / Q000097:blood; D008078:Cholesterol, LDL / Q000097:blood*; D003430:Cross-Sectional Studies; D005215:Fasting; D005260:Female; D006801:Humans; D006946:Hyperinsulinism / Q000097:blood*; D007328:Insulin / Q000097:blood*; D007333:Insulin Resistance; D017270:Lipoprotein(a) / Q000097:blood*; D008297:Male; D012044:Regression Analysis; D014280:Triglycerides / Q000097:blood
chemical_list: D001054:Apolipoproteins A; D008078:Cholesterol, LDL; D007328:Insulin; D017270:Lipoprotein(a); D014280:Triglycerides; D002784:Cholesterol