IR significantly blunted FMD after no treatment ( pre-IR FMD : 10.2 % 2.6 % ; post-IR FMD : 3.5 % 1.9 % , P < 0.01 ) but not after pioglitazone administration ( pre-IR FMD : 9.7 % 2.5 % ; post-IR FMD : 8.8 % 2.9 % , P = 0.11 ) .