title: Lower circulating irisin is associated with type 2 diabetes mellitus.
abstract: OBJECTIVE
  Irisin is a novel myokine secreted in response to PPAR-γ co-activator-1α (PGC-1α) activation. Earlier studies suggested that PGC-1α expression and activity were lower in myocytes in type 2 diabetes mellitus (T2DM). Therefore, we hypothesize that circulating irisin levels are lower in T2DM patients.
  
  
  METHODS
  In this observational study, we recruited 96 T2DM subjects and 60 non-diabetic control subjects. Among T2DM subjects, 38% were on insulin treatment, 78% were taking statins and 72% were taking renin-angiotensin system antagonists. Circulating irisin was quantified by ELISA and its association with markers of metabolic phenotype was analyzed by Pearson bivariate correlation and multiple linear regression.
  
  
  RESULTS
  Circulating irisin was significantly lower in individuals with T2DM compared with non-diabetic controls (T2DM 204 ± 72 ng/ml vs. non-diabetic control 257 ± 24 ng/ml, p < 0.0001). In non-diabetic subjects, circulating irisin was correlated with age (r = 0.398, p < 0.01), BMI (r = 0.387, p < 0.01), total cholesterol (r = 0.341, p < 0.01), total triglycerides (r = 0.299, p < 0.05), fasting blood glucose (r = 0.430, p < 0.01) and diastolic blood pressure (r = 0.306, p < 0.05). Multiple linear regression model revealed that BMI (β = 0.407, p = 0.012) and FBG (β = 0.315, p = 0.034) were associated with irisin in non-diabetic subjects after adjusting for multiple co-variates. However, similar analysis in T2DM subjects didn't reveal significant association between circulating irisin and major markers of metabolic phenotype.
  
  
  CONCLUSIONS
  Circulating irisin is lower in T2DM compared with non-diabetic controls. Plasma irisin levels appear to be associated with important metabolic factors in non-diabetic subjects but not in individuals with type 2 diabetes.
authors.affiliation: Clinical Research Unit, Khoo Teck Puat Hospital, Republic of Singapore.
authors.forename: Jian-Jun
authors.initials: JJ
authors.lastname: Liu
authors.forename: Melvin D S
authors.initials: MD
authors.lastname: Wong
authors.forename: Wan Ching
authors.initials: WC
authors.lastname: Toy
authors.forename: Clara S H
authors.initials: CS
authors.lastname: Tan
authors.forename: Sylvia
authors.initials: S
authors.lastname: Liu
authors.forename: Xiao Wei
authors.initials: XW
authors.lastname: Ng
authors.forename: Subramaniam
authors.initials: S
authors.lastname: Tavintharan
authors.forename: Chee Fang
authors.initials: CF
authors.lastname: Sum
authors.forename: Su Chi
authors.initials: SC
authors.lastname: Lim
mesh_terms: D000328:Adult; D000368:Aged; D015992:Body Mass Index; D016022:Case-Control Studies; D003924:Diabetes Mellitus, Type 2 / Q000097:blood* / Q000453:epidemiology* / Q000209:etiology; D015536:Down-Regulation; D005260:Female; D005353:Fibronectins / Q000097:blood*; D006801:Humans; D007328:Insulin / Q000097:blood; D007333:Insulin Resistance / Q000502:physiology; D008297:Male; D008875:Middle Aged; D012307:Risk Factors
chemical_list: C577593:FNDC5 protein, human; D005353:Fibronectins; D007328:Insulin