title: Ethnic differences in the relationship between insulin sensitivity and insulin response: a systematic review and meta-analysis.
abstract: OBJECTIVE
  Human blood glucose levels have likely evolved toward their current point of stability over hundreds of thousands of years. The robust population stability of this trait is called canalization. It has been represented by a hyperbolic function of two variables: insulin sensitivity and insulin response. Environmental changes due to global migration may have pushed some human subpopulations to different points of stability. We hypothesized that there may be ethnic differences in the optimal states in the relationship between insulin sensitivity and insulin response.
  
  
  METHODS
  We identified studies that measured the insulin sensitivity index (SI) and acute insulin response to glucose (AIRg) in three major ethnic groups: Africans, Caucasians, and East Asians. We identified 74 study cohorts comprising 3,813 individuals (19 African cohorts, 31 Caucasian, and 24 East Asian). We calculated the hyperbolic relationship using the mean values of SI and AIRg in the healthy cohorts with normal glucose tolerance.
  
  
  RESULTS
  We found that Caucasian subpopulations were located around the middle point of the hyperbola, while African and East Asian subpopulations are located around unstable extreme points, where a small change in one variable is associated with a large nonlinear change in the other variable.
  
  
  CONCLUSIONS
  Our findings suggest that the genetic background of Africans and East Asians makes them more and differentially susceptible to diabetes than Caucasians. This ethnic stratification could be implicated in the different natural courses of diabetes onset.
authors.affiliation: Division of Systems Medicine, Department of Pediatrics, Stanford University School of Medicine, Stanford, California, USA. kkodama@stanford.edu
authors.forename: Keiichi
authors.initials: K
authors.lastname: Kodama
authors.forename: Damon
authors.initials: D
authors.lastname: Tojjar
authors.forename: Satoru
authors.initials: S
authors.lastname: Yamada
authors.forename: Kyoko
authors.initials: K
authors.lastname: Toda
authors.forename: Chirag J
authors.initials: CJ
authors.lastname: Patel
authors.forename: Atul J
authors.initials: AJ
authors.lastname: Butte
mesh_terms: D044466:Asian People; D044383:Black People; D006801:Humans; D007328:Insulin / Q000378:metabolism; D007333:Insulin Resistance / Q000208:ethnology / Q000502:physiology*; D044465:White People
chemical_list: D007328:Insulin