INS and psoriasis: Nine months later, the patient’s glucose-lowering regimen remained unchanged, the psoriasis medication had been discontinued, and all laboratory results were within normal ranges except for a serum C-peptide level of <0.01 ng/mL (normal range: 1.1–4.4 ng/mL) and a serum insulin level of <0.20 μmol/L (normal range: 3.21–16.32 μmol/L).