GPT and Abdominal obesity: When we performed the correlation analysis adjusted for age, gender, HOMA and waist circumference as a marker of abdominal obesity, there were significant correlations between the serum RBP4 levels and the serum ALT and GGT levels (r = 0·2004, P = 0·0172; r = 0·3588, P < 0·0001, respectively).