title: Plasma Amyloid-β Peptides in Type 2 Diabetes: A Matched Case-Control Study.
abstract: Plasma amyloid-β (Aβ) levels have rarely been investigated in type 2 diabetes despite its known associations with Alzheimer's disease.
  
  
  
  To compare blood plasma Aβ concentrations (Aβ40 and Aβ42) in cognitively normal individuals with and without type 2 diabetes.
  
  
  
  Plasma Aβ40 and Aβ42 were measured in 194 participants with diabetes recruited from the community-based Fremantle Diabetes Study Phase II cohort (mean age 71 years, 59% males) and 194 age-, sex-, and APOEɛ4 allele-matched, control subjects without diabetes from the Australian Imaging, Biomarkers and Lifestyle Study using a multiplex microsphere-based immunoassay.
  
  
  
  Plasma Aβ40 and Aβ42 were normally distributed in the controls but were bimodal in the participants with diabetes. Median Aβ40 and Aβ42 concentrations were significantly lower in those with type 2 diabetes (Aβ40 median [inter-quartile range]: 125.0 [52.6-148.3] versus 149.3 [134.0-165.6] pg/mL; Aβ42: 26.9 [14.5-38.3] versus 33.6 [28.0-38.9] pg/mL, both p < 0.001) while the ratio Aβ42:Aβ40 was significantly higher (0.26 [0.23-0.32] versus 0.22 [0.19-0.25], p < 0.001). After adjustment, participants with diabetes and plasma Aβ40 levels in the low peak of the bimodal distribution were significantly more likely to have normal to high estimated glomerular filtration rates (odds ratio (95% CI): 2.40 (1.20-4.80), p = 0.013) although the group with diabetes had lower renal function overall.
  
  
  
  Type 2 diabetes is associated with altered plasma concentrations of Aβ peptides and is an important source of variation that needs to be taken into account when considering plasma Aβ peptides as biomarkers for Alzheimer's disease.
authors.affiliation: School of Medicine and Pharmacology, University of Western Australia, Fremantle, WA, Australia.
authors.forename: Kirsten E
authors.initials: KE
authors.lastname: Peters
authors.affiliation: School of Medicine and Pharmacology, University of Western Australia, Fremantle, WA, Australia.
authors.forename: Wendy A
authors.initials: WA
authors.lastname: Davis
authors.affiliation: School of Medical Sciences, Edith Cowan University, Joondalup, WA, Australia.
authors.forename: Kevin
authors.initials: K
authors.lastname: Taddei
authors.affiliation: School of Medical Sciences, Edith Cowan University, Joondalup, WA, Australia.|Department of Biomedical Sciences, Macquarie University, NSW, Australia.
authors.forename: Ralph N
authors.initials: RN
authors.lastname: Martins
authors.affiliation: The Florey Institute, University of Melbourne, Parkville, Vic., Australia.
authors.forename: Colin L
authors.initials: CL
authors.lastname: Masters
authors.affiliation: School of Medicine and Pharmacology, University of Western Australia, Fremantle, WA, Australia.
authors.forename: Timothy M E
authors.initials: TM
authors.lastname: Davis
authors.affiliation: School of Medicine and Pharmacology, University of Western Australia, Fremantle, WA, Australia.
authors.forename: David G
authors.initials: DG
authors.lastname: Bruce
mesh_terms: D000368:Aged; D016229:Amyloid beta-Peptides / Q000097:blood*; D053327:Apolipoprotein E4 / Q000235:genetics; D015415:Biomarkers / Q000097:blood; D016022:Case-Control Studies; D015331:Cohort Studies; D003924:Diabetes Mellitus, Type 2 / Q000097:blood* / Q000235:genetics; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D010446:Peptide Fragments / Q000097:blood*
chemical_list: D016229:Amyloid beta-Peptides; D053327:Apolipoprotein E4; D015415:Biomarkers; D010446:Peptide Fragments; C078592:amyloid beta-protein (1-40); C075222:amyloid beta-protein (1-42)
keywords: Alzheimer’s disease; amyloid-β; blood biomarkers; peptides; type 2 diabetes mellitus