Generally in leukemia patients there are long term complications related to the treatments given including the usually curative treatment called "Allogenic hematopoietic stem cell transplantation".
The treatment involves taking sane stem cells from a donor and transplant them in the patient after depleting his bone morrow by total body radiation or chemotherapy (radiation/chemotherapy before transplantation is called pre transplantation preparation).
After the cells are transplanted they start to recognize the cancerous cells that are still present as foreign cells and starts attacking them which protects the body from these cell. The problem is that these cells also recognize the normal cells of different organs of the patient as foreign cells and start attacking them leading to one of the most common complication of transplantation treatment called Graft versus host disease (GVHD). It is a type of autoimmune disease where different organs in the body are attacked by the new cells formed from the transplanted stem cells, for example metabolic syndrome could be a complication of the transplantation itself through GVHD. (https://www.astctjournal.org/article/S1083-8791(16)30079-9/fulltext)
Here is a link that explains GVHD without complicated medical terms:
The preparation process for transplantation in many cases involves total body radiation which could lead to abnormalities in endocrine system due to the effect of radiation on glandular cells. (https://www.karger.com/article/fulltext/495698).
These alterations could manifest as sicca syndrome (lacrimal and salivary glands cannot secrete), diabetes (beta cells are harmed in pancreas) and so on.