TY - JOUR

T1 - Glucose intolerance in the West African Diaspora

T2 - a skeletal muscle fibre type distribution hypothesis

AU - Nielsen, Jannie

AU - Christensen, Dirk Lund

PY - 2011

Y1 - 2011

N2 - In the United States, Black Americans are largely descendants of WestAfrican slaves; they have a higher relative proportion of obesity and experiencea higher prevalence of diabetes than White Americans. However,obesity rates alone cannot explain the higher prevalence of type 2 diabetes.Type 2 diabetes is characterized by insulin resistance and beta-cell dysfunction.We hypothesize that the higher prevalence of type 2 diabetes in AfricanAmericans (as compared to White Americans) is facilitated by an inheritedhigher percentage of skeletal muscle fibre type II and a lower percentage ofskeletal muscle fibre type I. Skeletal muscle fibre type II is less oxidative andmore glycolytic than skeletal muscle fibre type I. Lower oxidative capacity isassociated with lower fat oxidation and a higher disposal of lipids, which arestored as muscular adipose tissue in higher amounts in Black compared toWhite Americans. In physically active individuals, the influence of musclefibre composition will not be as detrimental as in physically inactive individuals.This discrepancy is caused by the plasticity in the skeletal musclefibre characteristics towards a higher activity of oxidative enzymes as aconsequence of physical activity. We suggest that a higher percentage ofskeletal muscle fibre type II combined with physical inactivity has an impacton insulin sensitivity and high prevalence of type 2 diabetes in Blacks of WestAfrican ancestry.

AB - In the United States, Black Americans are largely descendants of WestAfrican slaves; they have a higher relative proportion of obesity and experiencea higher prevalence of diabetes than White Americans. However,obesity rates alone cannot explain the higher prevalence of type 2 diabetes.Type 2 diabetes is characterized by insulin resistance and beta-cell dysfunction.We hypothesize that the higher prevalence of type 2 diabetes in AfricanAmericans (as compared to White Americans) is facilitated by an inheritedhigher percentage of skeletal muscle fibre type II and a lower percentage ofskeletal muscle fibre type I. Skeletal muscle fibre type II is less oxidative andmore glycolytic than skeletal muscle fibre type I. Lower oxidative capacity isassociated with lower fat oxidation and a higher disposal of lipids, which arestored as muscular adipose tissue in higher amounts in Black compared toWhite Americans. In physically active individuals, the influence of musclefibre composition will not be as detrimental as in physically inactive individuals.This discrepancy is caused by the plasticity in the skeletal musclefibre characteristics towards a higher activity of oxidative enzymes as aconsequence of physical activity. We suggest that a higher percentage ofskeletal muscle fibre type II combined with physical inactivity has an impacton insulin sensitivity and high prevalence of type 2 diabetes in Blacks of WestAfrican ancestry.

U2 - 10.1111/j.1748-1716.2011.02272.x

DO - 10.1111/j.1748-1716.2011.02272.x

M3 - Journal article

C2 - 21382179

VL - 202

SP - 605

EP - 616

JO - Acta Physiologica

JF - Acta Physiologica

SN - 1748-1708

IS - 4

ER -