Late Onset Type 1 Diabetes Mellitus Associated with Single Positive for Insulinoma-associated Tyrosine Phosphatase-like Protein-2 (IA-2) Antibody

Abstract

A 62-year-old woman with mildly elevated fasting plasma glucose at 119mg/dl and HbA_1c of 6.2% in July 1999 experienced thirst and weight loss in January 2000 and was hospitalized to assess elevated plasma glucose of 520 mg/dl and HbAic of 12.4% and for positive urine ketone body.Her fasting serum CPR concentration was 24μg/day and urinary CPR concentration 0.3ng/ml, indicated decreasing insulin secretion.Although both her glutamic acid dehydrogenase (GAD) antibody level and islet cell antibody (ICA) tests were negative, she was diagnosed with type 1 diabetes mellitus due to high IA-2 antibody (28.7U/ml).She was treated with insulin during hospitalization.Her diabetic control was good without insulin therapy for 6 months after discharge, but she later resumed insulin therapy, which continues today.IA-2 antibody has been continuously positive, but her GAD antibody remains negative.She carries both human leukocyte antigen (HLA) haplotype, which is a genetic risk for Japanese type 1 diabetes mellitus, DRB 1*0405-DQB 1*0401 and DRB 1*0901-DQB 1*0303.