A high level of free fatty acids alone is not necessarily a disease, but can also be caused by physiological factors, such as starvation, after exercise, etc. Transient high levels of free fatty acids can occur. This is because free fatty acid is one of the substances formed by the decomposition of neutral fat. When liver sugar, the energy required for muscle activity, is depleted, adipose tissue will decompose neutral fat into free fatty acid to be used as energy, so when the body is starving or after exercise, high free fatty acid may occur. The concentration of free fatty acids in serum is related to lipid metabolism, glucose metabolism, and endocrine function. If free fatty acids are significantly elevated, it is still necessary to be alert to the possibility of certain diseases, such as diabetes, severe liver disorders, hyperthyroidism, etc. High free fatty acids can produce oxidative stress, which induces insulin resistance. When insulin resistance increases, compensatory insulin secretion decreases or both, the disease gradually progresses to hypoglycemic tolerance and diabetes. Generally, after finding elevated free fatty acids, do not worry too much first, and look at it together with other examination indexes. If there is only a single high free fatty acid, you can first review it at a later date to exclude physiological factors causing it. If there are other abnormalities, such as elevated blood glucose, further examination is recommended to clarify the specific cause.