title: Vascular smooth muscle function in type 2 diabetes mellitus: a systematic review and meta-analysis.
abstract: OBJECTIVE
  In type 2 diabetes, in contrast to the well-documented endothelial dysfunction, studies assessing vascular smooth muscle (VSM) function have yielded discrepant results over the last two decades. We therefore sought to determine whether or not VSM function is impaired in individuals with type 2 diabetes.
  
  
  METHODS
  We conducted a systematic search of MEDLINE, Cochrane, Scopus and Web of Science databases, from their respective inceptions until December 2012, for articles evaluating VSM function in individuals with type 2 diabetes. A meta-analysis was performed to compare the standardised mean difference (SMD) in VSM function between individuals with type 2 diabetes and age-matched controls. Subgroup analyses and meta-regression were used to identify sources of heterogeneity.
  
  
  RESULTS
  Twenty-seven articles (1,042 individuals with type 2 diabetes and 601 control subjects) were included in this analysis. VSM function was significantly impaired in diabetic compared with control subjects (SMD -0.68, 95% CI -0.84, -0.52; p < 0.001). Although moderate heterogeneity among studies was found (I (2) = 52%), no significant publication bias was detected. Subgroup analyses showed a further decline in VSM function assessed in the microcirculation compared with the macrocirculation of individuals with type 2 diabetes (p = 0.009). In meta-regression, VSM function in the microcirculation was inversely associated with BMI and triacylglycerols and was positively associated with HDL-cholesterol.
  
  
  CONCLUSIONS
  In addition to the endothelium, the VSM is a source of vascular dysfunction in type 2 diabetes. An exacerbation of VSM function in the microcirculation may be a distinctive feature in type 2 diabetes.
authors.affiliation: LAPEC EA4278, Avignon University, 33 rue Louis Pasteur, F-84000, Avignon, France. david.montero.barril@gmail.com
authors.forename: David
authors.initials: D
authors.lastname: Montero
authors.forename: Guillaume
authors.initials: G
authors.lastname: Walther
authors.forename: Antonia
authors.initials: A
authors.lastname: Pérez-Martin
authors.forename: Nestor
authors.initials: N
authors.lastname: Vicente-Salar
authors.forename: Enrique
authors.initials: E
authors.lastname: Roche
authors.forename: Agnès
authors.initials: A
authors.lastname: Vinet
mesh_terms: D003924:Diabetes Mellitus, Type 2 / Q000378:metabolism / Q000473:pathology* / Q000503:physiopathology; D006801:Humans; D009131:Muscle, Smooth, Vascular / Q000378:metabolism / Q000473:pathology* / Q000503:physiopathology