Background and aims The relationship between gamma-glutamil transferase (GGT) activity and obesity-induced disorders is still an open question. Therefore, we aimed to examine the association between GGT activity and metabolic risk factors in overweight/obese adolescent girls.

Methods A total of 70 overweight/obese adolescent girls (mean age 17.6±1.2 years) and 30 normal weight age-matched controls were included in this cross-sectional study. Anthropometric measures (body weight, body height and waist circumference) were obtained. Body mass index (BMI) and BMI z-score were calculated. Biochemical parameters: fasting glucose, insulin, GGT activity, lipid parameters [total cholesterol, triglycerides (TG), LDL-cholesterol and HDL-cholesterol] were measured. Atherogenic index (TG/HDL-cholesterol) and non-HDL-cholesterol, as well as insulin resistance (HOMA-IR) were calculated.

Results The highest number of overweight/obese adolescent girls were in the highest GGT activity tertile group, whereas the highest number of normal weight counterparts were in the lowest GGT activity tertile group (X²=9.214, p=0.002). Furthermore, the highest levels of insulin, HOMA-IR and TG/HDL-cholesterol ratio, but the lowest levels of HDL-cholesterol were observed in the highest GGT activity tertile group (p<0.001, respectively). Multiple linear regression analysis revealed that the greatest influence on GGT activity variability showed HOMA-IR (Beta=0.216, p=0.035), (R²=0.167; p<0.001).

Conclusion Higher gamma-glutamil transferase activity could be the useful marker of insulin resistance in overweight/obese adolescent girls.