HDL-C refers to high-density lipoprotein cholesterol, which can be low for many reasons, such as atherosclerosis, acute infection, diabetes, and chronic renal failure. In addition, HDL-C also shows a gradual decline with age. HDL-C is the good cholesterol, which can prevent the occurrence and development of coronary heart disease and is a protective factor against atherosclerosis. Therefore, there are now many drugs used clinically to intervene and raise HDL-C, such as niacin.