GPT and chronic kidney disease: Individuals with higher quartiles of GGT levels were older, had a higher BMI, more commonly had a low income (lowest 25%), were more commonly current smokers, heavy alcohol drinkers, less commonly performed regular physical activity, more commonly had hypertension, type 2 diabetes, dyslipidemia, and CKD, had higher systolic BP, diastolic BP, fasting glucose, total cholesterol, low-density lipoprotein cholesterol, triglyceride, AST, and ALT levels, and had lower high-density lipoprotein cholesterol levels and estimated glomerular filtration rates (all p for trend < 0.001).