title: Effects of hyperlipidaemia on plasma apolipoprotein M levels in patients with type 2 diabetes mellitus: an independent case-control study.
abstract: BACKGROUND
  Apolipoprotein M (apoM) is mainly enriched in high-density lipoprotein (HDL) cholesterol and is slightly present in low-density lipoprotein (LDL) cholesterol and very low-density lipoprotein cholesterol. apoM is involved in HDL formation and HDL-mediated reverse cholesterol transport. apoM is also associated with hyperlipidaemia and type 2 diabetes mellitus (T2DM). Significantly high plasma apoM levels are detected in hyperlipidaemia mice with a defective LDL receptor. By contrast, low plasma apoM levels are observed in patients with T2DM, which is often accompanied with hyperlipidaemia. However, the underlying mechanism of this condition is poorly understood. This research aims to examine the changes in apoM levels in patients with hyperlipidaemia and to determine the effects of hyperlipidaemia on plasma apoM levels in patients with T2DM.
  
  
  METHODS
  This study included patients with hyperlipidaemia (n = 79), patients with T2DM but without hyperlipidaemia (n = 125), patients with T2DM and hyperlipidaemia (n = 98), and healthy controls (n = 105). Their plasma apoM concentrations were measured with enzyme-linked immunosorbent assay.
  
  
  RESULTS
  The average plasma apoM concentrations were 18 % higher in the hyperlipidaemia group (26.63 ± 10.35 ng/μL) than in the healthy controls (22.61 ± 10.81 ng/μL, P <0.01). The plasma apoM concentrations were lower in the T2DM without hyperlipidaemia group (18.54 ± 10.33 ng/μL, P <0.01) and the T2DM with hyperlipidaemia group (19.83 ± 7.41 ng/μL, P <0.05) than in the healthy controls. Similar to apoA-I (1.29 ± 0.33 g/L vs. 1.28 ± 0.31 g/L, P >0.05), the plasma apoM concentrations in the T2DM with hyperlipidaemia group did not significantly differ from those in the T2DM without hyperlipidaemia group (P >0.05). Multivariate linear regression analysis showed that hyperlipidaemia (β = 5.18, P = 0.007) is an independent promoting factor of plasma apoM levels and diabetes (β = -3.09, P = 0.005) is an inhibiting factor of plasma apoM levels.
  
  
  CONCLUSIONS
  Plasma apoM concentrations are higher in patients with hyperlipidaemia than in healthy controls. Low plasma apoM levels in patients with T2DM are likely caused by diabetes but are not induced by hyperlipidaemia.
authors.affiliation: Anhui Province Key Laboratory of Biological Macro-molecules Research (Wannan Medical College), Wuhu, China.
authors.forename: Puhong
authors.initials: P
authors.lastname: Zhang
authors.affiliation: Anhui Province Key Laboratory of Biological Macro-molecules Research (Wannan Medical College), Wuhu, China.|Department of Endocrinology and Genetic Metabolism, Yijishan Hospital of Wannan Medical College, Wuhu, China.
authors.forename: Jialin
authors.initials: J
authors.lastname: Gao
authors.affiliation: Department of Clinical Laboratory, Yijishan Hospital of Wannan Medical College, Wuhu, China.
authors.forename: Chun
authors.initials: C
authors.lastname: Pu
authors.affiliation: Department of Clinical Laboratory, Yijishan Hospital of Wannan Medical College, Wuhu, China.
authors.forename: Gang
authors.initials: G
authors.lastname: Feng
authors.affiliation: Department of Biochemistry and Molecular Biology, Wannan Medical College, 22 West Wenchang Road, Wuhu, 241002, People's Republic of China.|Anhui Province Key Laboratory of Biological Macro-molecules Research (Wannan Medical College), Wuhu, China.
authors.forename: Lizhuo
authors.initials: L
authors.lastname: Wang
authors.affiliation: Department of Clinical Laboratory, Yijishan Hospital of Wannan Medical College, Wuhu, China.
authors.forename: Lizhu
authors.initials: L
authors.lastname: Huang
authors.affiliation: Department of Clinical Laboratory, Yijishan Hospital of Wannan Medical College, Wuhu, China.
authors.forename: Qingsong
authors.initials: Q
authors.lastname: Tao
authors.affiliation: Department of Biochemistry and Molecular Biology, Wannan Medical College, 22 West Wenchang Road, Wuhu, 241002, People's Republic of China. yaozhang_wnmc@yahoo.com.|Anhui Province Key Laboratory of Biological Macro-molecules Research (Wannan Medical College), Wuhu, China. yaozhang_wnmc@yahoo.com.
authors.forename: Yao
authors.initials: Y
authors.lastname: Zhang
mesh_terms: D000328:Adult; D000368:Aged; D000818:Animals; D001053:Apolipoproteins / Q000097:blood*; D000075243:Apolipoproteins M; D008078:Cholesterol, LDL / Q000097:blood*; D003924:Diabetes Mellitus, Type 2 / Q000097:blood* / Q000473:pathology; D005260:Female; D006801:Humans; D006949:Hyperlipidemias / Q000097:blood* / Q000473:pathology; D016014:Linear Models; D054834:Lipocalins / Q000097:blood*; D008297:Male; D051379:Mice; D008875:Middle Aged
chemical_list: C400523:APOM protein, human; D001053:Apolipoproteins; D000075243:Apolipoproteins M; D008078:Cholesterol, LDL; D054834:Lipocalins
keywords: Apolipoproteins; Diabetes; Dyslipidaemia; HDL; Lipids