GPT and Insulin resistance: ALT: alanine aminotransferase; AST: aspartate aminotransferase; CRP: C-reactive protein; BMI: body mass index; HbA1c: hemoglobin A1c; HOMA-IR: homeostasis model assessment—insulin resistance; PKU: phenylketonuria; SD: standard deviation; SMM: lean muscle mass; WHR: waist-to-hip ratio.