A Challenging Case of Diabetes in a Patient With XXYY Syndrome.

48 XXYY syndrome is a rare polyploidy often compared with Klinefelter syndrome because of shared features such as tall stature, neurocognitive diseases, hypogonadism, and cardiac malformations. This population is believed to be predisposed to type 2 diabetes because of the presence of hypogonadism and central adiposity. We present a patient with XXYY syndrome who had an atypical and difficult-to-manage diabetes presentation. The patient was nonadherent to medication regimen with poorly controlled diabetes and hemoglobin A1c ranging from 12% to 14% (16.5-19.6 mmol/L). He lacked history of diabetes ketoacidosis, raising the question of maturity-onset diabetes of the young. Workup was negative for glutamic acid decarboxylase-65 and pancreatic islet cell antibody testing. Genetic testing for 5-gene panel for maturity-onset diabetes of the young was also negative. Distinct parts of his presentation make an accurate diabetes diagnosis very challenging. Clinicians should be aware of diabetes associations in patients with XXYY syndrome for optimization of care.