HDL cholesterol 1.2mmol/L is not serious and the value is within the normal reference range. 1. The normal reference range of HDL cholesterol is 1.03-2.07mmol/L, so HDL cholesterol 1.2mmol/L is within the normal range and does not represent any serious condition. It should be noted that different hospitals have different testing instruments, the value of the standard will be different, to the local three hospitals testing standards shall prevail. 2. HDL cholesterol is mainly synthesized in the liver and small intestine, mainly containing protein, cholesterol, phospholipids, a small amount of fatty acids and other substances. Its main function is to resist atherosclerosis, and it can transport cholesterol from extrahepatic tissues to the liver for decomposition, metabolism, and excretion. Higher HDL cholesterol values have a certain protective effect on cardiovascular system. 3. HDL cholesterol is closely related to the development of coronary heart disease and is a diagnostic indicator of cardiovascular disease. The results of this test should be analyzed and judged by a professional doctor in conjunction with the patient’s medical history, symptoms, and other relevant tests. It is recommended that patients standardize their treatment under the guidance of their doctors.