GPT and diabetes mellitus: (2) From the longitudinal relationship between ALT, HDL-C and age, ALT usually decreases gradually with age (51, 52), while HDL-C usually changes less (48, 53, 54); these characteristics will further lead to a reduction in ALT/HDL-C ratio values, thereby reducing the risk of diabetes related to ALT/HDL-C ratio in people over 60 years old.