Transient neonatal diabetes mellitus, type 4, type 1 diabetes mellitus, or MODY: which disease is it, anyway?

A 30year-old Hispanic male who presented with transient neonatal diabetes mellitus at 4 months has been intensively studied with 12 islet-cell secretagogues from 4 months to 24 years. He was both ICA- and GAD-65-negative, but at 28 years was diagnosed with hypothyroidism due to positive thyroperoxidase antibodies. The course of his disease(s) and the various presentations of hyperglycemia are documented and illustrated by the responses in islet cell hormone secretion, namely, insulin, glucagon, and C-peptide. Insulin secretion gradually fell over 24 years, glucagon secretion persisted from infancy to 24 years but was only minimal during i.v. glucose at 24 years, and C-peptide secretion remained normal, although modest, throughout the 24 years. These data suggest that, despite changing presentations of diabetes mellitus over time, the islets continued to process proinsulin, although the patient required insulin therapy.