Abstract
A 66-year-old man diagnosed with diabetes mellitus in 1990 mainly treated by diet had hemoglobin A1c ranging from 6.2% to 8.9% before 1998, but exceeding 10.0% after 1998. He was referred due to sulfonylurea failure in September 2000. Since casual plasma glucose (202 mg/dl), hemoglobin A1c (14.5%) and antiglutamic acid decarboxylase (GAD) 65 antibody titer (79.4 U/ml) were all elevated and small intestinal tumors were detected by computed tomography (CT), he was admitted. Urinary C-peptide (CPR) was low (6.4μg/day), andbothanti-insulin antibody and anti tyrosine phosphatase-like protein islet antigen-2 (IA-2) antibody were negative. Although the histology of the small intestinal tumors was found to be gastrointestinal stromal tumor (GIST) and urinary CPR was elevated (77.9μg/day) Postoperatively, anti-GAD 65 antibody titer remained high.An examination of human leukocyte antigen (HLA) showed 3 resistant alleles- DRB1*1502, *0403, and DQB1* 0601- and 1 susceptible allele-DQB1*0302-to type 1 diabetes mellitus. Since resistance is said to be dominant in susceptibility, DRB1*0403-DQB1*0302 is a neutral or resistant haplotype and DRB1*1502-DQB1*0601 is a resistant haplotype to type1diabetes.This case shows that slowly progressive type1diabetes with resistant haplotypes can become insulin-independent after the removal of impaired glucose tolerance due to factors such assmall intestinal tumors.
