Clinical and genetic characteristics of GAD-antibody positive patients initially diagnosed as having type 2 diabetes

Diabetes Res Clin Pract. 2004 Nov;66(2):163-71. doi: 10.1016/j.diabres.2004.02.019.


The present study was conducted to clarify the clinical and genetic characteristics of the diabetic patients who have antibodies to glutamic acid decarboxylase (GADab) but are diagnosed initially as type 2 diabetes because of the slow progression. Fifty-five GADab+ patients and 137 GADab- patients were recruited. The GADab+ patients were divided into two subgroups according to their antibody titers. The high-titer subgroup (Ab > or = 20 U/ml) had lower urinary C-peptide concentrations, and was assigned insulin therapy more often than the GADab- patients. In contrast to the high-titer subgroup, clinical parameters in the low-titer subgroup were similar to the GADab- diabetic patients. The urinary C-peptide levels correlated negatively with the GADab titer in the GADab+ patients. Analysis of type 1 diabetes-susceptible HLA alleles revealed high frequencies of the B54 and DRB1*0405 allele, but not the B61 and DRB1*0901 alleles, in the high-titer subgroup, whereas the frequency of the protective DRB1*1502 allele was decreased. The GADab+ patients with the B54 allele had higher GADab titers and lower urinary C-peptide excretion than patients without this allele. These data indicated that patients with a high-GADab titer share the autoimmune background characteristic of type 1 diabetes.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Alleles
  • Autoantibodies / blood*
  • Autoimmunity / genetics
  • C-Peptide / urine
  • Diabetes Mellitus, Type 1 / genetics
  • Diabetes Mellitus, Type 2 / blood*
  • Diabetes Mellitus, Type 2 / genetics
  • Diabetes Mellitus, Type 2 / physiopathology*
  • Diabetes Mellitus, Type 2 / urine
  • Female
  • Genetic Predisposition to Disease / genetics
  • Glutamate Decarboxylase / immunology*
  • HLA Antigens / genetics
  • Humans
  • Male
  • Middle Aged


  • Autoantibodies
  • C-Peptide
  • HLA Antigens
  • Glutamate Decarboxylase