Cold legs can be caused by physiologic factors or pathologic factors such as diabetes or rheumatoid arthritis. The specific situation should be confirmed by a physician to determine the diagnosis. 1. Physiological factors: When the temperature changes suddenly or in the air-conditioned room, the body wears less clothing, then the cold legs will occur. 2. Pathological factors (1) Diabetes mellitus: this disease can cause peripheral neuropathy can lead to peripheral vascular damage in the lower limbs, and at this time there will be cold legs. (2) Rheumatoid arthritis: Rheumatoid arthritis patients have cold legs and feet, especially in the morning and at night, and the cold legs and feet are mainly caused by insufficient blood circulation in the legs. It is recommended that when this symptom occurs, one should go to the hospital for examination. This symptom may also be caused by other factors, such as vascular diseases. The cause of the disease should be clarified and should be treated under the guidance of a physician.