A REDUCED GLUT-4 CONTENT IN ADIPOSE-TISSUE IS NOT AN EARLY DEFECT IN THE DEVELOPMENT OF HUMAN INSULIN-RESISTANCE

In order to investigate whether Glut 4 content is reduced in the adipose tissue at an early stage of human insulin resistance, among 30 non-obese (BMI <27) non-diabetic (by oral glucose tolerance test) volunteers: we selected 3 groups of 10 subjects each according to their insulin sensitivity at an i,v, insulin tolerance test (K-itt values). We then compared the Glut ii content in the adipose tissue specimens from 7 of the most insulin sensitive and 8 of the most insulin resistant subjects, No difference was observed in tire average Glut 4 content between the 2 groups (0.45+/-0.05 arbitrary densitometric units in insulin sensitive subjects vs 0.61+/-0.16 in insulin-resistant subjects), No significant correlation was observed between Glut 4 content in adipose tissue nor in vivo insulin sensitivity (K-itt values), plasma insulin levels 120 win after an oral glucose load, or BMI. In contrast to Glut 4 content, insulin action was already reduced in adipose tissue from insulin-resistant subjects, as shown by the significantly (p<0,05) impaired ability to stimulate receptor tyrosine-kinase activity, a key step in the insulin signalling cascade, In conclusion we demonstrate that, at an early stage, human insulin resistance is not associated to a reduced Glut 4 content in adipose tissue.