Hi, Thanks for writing in. Your mother has an advanced stage of breast cancer and needs treatment targeted to the cancer spread. In this situation, the cancer cells might be controlled by chemotherapy and radiation. Her sugar levels are high and this can cause additional health problems during her treatment. Swelling of limbs might be an emergency like deep vein thrombosis. You should urgently consult her doctors and get a D dimer blood test and lower limb Doppler scan done to know if there are any clots in the deep veins of legs. This is an emergency and must be considered first. If she does not have DVT then the swelling of leg might happen when there is extra fluid collection in the limbs and this takes place in the tissues below the skin and is also called subcutaneous edema. Such a situation might arise during cancer treatment and due to diabetes or reduced kidney or heart function and needs to be treated. Please do not worry.