Unmasking Ketosis-Prone Diabetes in a Young Adult.

Ketosis-prone diabetes (KPD) is a unique clinical entity that does not fit the classic phenotypes of type 1 diabetes mellitus (T1DM) or type 2 diabetes mellitus (T2DM), although it can present similarly with severe hyperglycemia or diabetic ketoacidosis (DKA). This report describes a patient initially diagnosed with type 2 diabetes mellitus who was subsequently suspected to have ketosis-prone diabetes based on his clinical course. A 22-year-old man presented to the emergency department (ED) with hyperglycemia and was diagnosed with new-onset type 2 diabetes. He was closely monitored by his primary care physician (PCP) and outpatient pharmacist but continued to experience hyperglycemia. He was prescribed increasing doses of insulin, reaching up to 56 units of basal insulin nightly and 12 units of prandial insulin. Antibody testing was mildly elevated, although determined to be clinically insignificant. The patient utilized continuous glucose monitoring (CGM), and after several months of insulin therapy, he experienced hypoglycemic episodes. Consequently, he was titrated off all insulin therapy and successfully maintained euglycemia for eight months before experiencing disease relapse. Ketosis-prone diabetes is challenging to diagnose and remains under-recognized. The Aβ classification system differentiates patients based on the presence or absence of autoantibodies and the presence or absence of β-cell functional reserve. We suspect this patient's presentation is most consistent with the A-β+ phenotype. As indicated by this case, the most challenging management often occurs in the subacute period when β-cell function is unknown. This case underscores the importance of recognizing ketosis-prone diabetes as a distinct clinical entity and highlights the value of close, multidisciplinary team follow-up for chronic management.