Abstract

BACKGROUND
American Diabetes Association (ADA) proposed new criteria for the classification of diabetic patients, which were mainly based on the presence of autoimmune markers. But it is questionable if we can apply the new ADA criteria to Korean type 1 diabetic patients directly. In this study, we measured several autoantibodies to islet cell in Korean subjects with typical and atypical clinical manifestations of type 1 diabetes mellitus. And mutation of mitochondrial DNA was analyzed in the same patients. METHODS: We measured fasting serum C-peptide in 1870 diabetic patients attending the diabetes clinic of Asan Medical Center. Among the 117 patients with fasting serum C-peptide less than 0.6 ng/mL, glucagon-stimulated C-peptide was measured, and 57 Patients showed the level less than 1 ng/mL and they were diagnosed as type 1 diabetic patients. They were subgrouped into typical (n=26, needed insulin injection within 1 year after diagnosis) and atypical (n=30, did not need insulin for more than l year after diagnosis) type 1 diabetic patients. ICA was measured by indirect immunofluorescence method. Anti-GAD antibody was measured by radioimmunoassay. Anti-ICA512 antibody was measured by western blotting. Mitochondrial DNA 3243 mutation was detected using restriction enzyme Apa-I digestion of the amplified genomic DNA from the subjects. RESULTS: 1) Median age of onset was 40 years for atypical type 1 diabetes patients, while it was 27.5 years for typical type 1 diabetes patients. Average duration of insulin requirement was 0.18 years for typical group and 5.73 years for atypical group. In this series, only typical type 1 diabetic patients experienced diabetic ketoacidosis. 2) Only 50 % of typical type 1 diabetic patients and 47 % of atypical type 1 diabetic patients had at least one autoantibody among ICA, anti-GAD antibody and anti-ICA512 antibody. 3) Mitochondrial DNA 3243 point mutation was detected in 3 patients with atypical type 1 diabetes (10 %), but it was not found in patients with typical type 1 diabetes. CONCLUSION: These results suggest that the prevalence of autoantibodies in Korean type 1 diabetic patients was lower than that reported in Caucasians irrespective of clinical features. Therefore, it may not be easy to apply this new diabetes classification of ADA to Korean type 1 diabetic patients. In addition, mitochondrial DNA mutation may be responsible for some of the Korean atypical type 1 diabetic patients.

• Keywords: Key Words;Type 1 diabetes mellitus;Islet cell autoantibody;Mitochondrial DNA mutation;