A recent study from the European Society for Blood and Marrow Transplantation (EBMT) found that in patients transplanted for a hematological malignancy from a matched sibling or unrelated donor between 2010 and 2018, 4.4% had pre-transplantation diabetes, defined as diabetes requiring treatment with insulin or oral hypoglycemics but not diet alone, and 3.9% had pre-transplant obesity, defined as having a BMI ≥ 35 kg/m2 [23]. This evidence concerns the gene INS and obesity due to melanocortin 4 receptor deficiency.