Relation of triglyceride stores in skeletal muscle cells to central obesity and insulin sensitivity in European and South Asian men

Aims/hypothesis. To compare the relation between intramyocellular lipid con tent, central obesity and insulin sensitivity in Europeans and South Asians . Methods. Cross-sectional study of 40 South Asian and European non-diabetic men matched for age and body mass index. We measured intramyocellular lipid by proton magnetic resonance spectroscopy of soleus muscle, insulin sensit ivity by the short insulin tolerance test, per cent body fat by dual-energy x-ray absorptiometry and visceral fat by single-slice computed tomography of the abdomen. Results. South Asians compared with Europeans had a higher mean per cent bo dy fat (26.8 % vs 22.5 %, p = 0.05) and lower insulin sensitivity (mean +/- SEM 2.4 +/- 0.2 vs 3.4%/min +/- 0.3, p = 0.013). Mean (+/- SEM) intramyoce llular lipid content was higher in South Asians than in Europeans (72.1 +/- 7.5 vs 53.6 +/- 4.9 mmol/kg dry weight, p = 0.046). In Europeans intramyoc ellular lipid was correlated with per cent body fat (r = 0.50 p = 0.028), w aist:hip ratio (r = 0.74, p < 0.001), visceral fat (r = 0.62, p = 0.004) an d insulin sensitivity (r = -0.53, p = 0.016). In South Asians intramyocellu lar lipid was not significantly related to insulin sensitivity or obesity, and the strongest associations of insulin sensitivity were with fasting pla sma triglyceride and waist:hip ratio. Conclusion/interpretation. The association of intramyocellular lipid with i nsulin sensitivity and obesity in Europeans is consistent with the hypothes is that muscle triglyceride mediates the effect of obesity on insulin sensi tivity. The absence of a similar relation of insulin sensitivity to intramy ocellular lipid in South Asians suggests that other mechanisms underlie the high insulin resistance observed in this group.