Low prevalence of autoimmune diabetes markers in a mixed ethnic population of Singaporean diabetics

Intern Med J. Jan-Feb 2004;34(1-2):24-30. doi: 10.1111/j.1444-0903.2004.00482.x.

Abstract

Background: Circulating antibodies to glutamic acid decarboxylase (GADab) and tyrosine phosphatase-like molecule IA-2 (IA-2ab) are major indicators for auto-immune destruction of pancreatic islet cells. They identify a majority of Caucasians with type 1 diabetes and approximately 50% of Asians, providing evidence of an idiopathic aetiology in the latter. The present study investigated these autoantibodies in a mixed ethnic group.

Methods: Hospital clinic patients with clinically defined type 1 (n = 93) and type 2 (n = 300) diabetes and representing Singapore's major ethnic groups--Chinese, Indians and Malays--were studied. GADab and IA-2ab frequencies, and association of autoimmunity status with clinical and biochemical profiles were analysed.

Results: Radio-immunoprecipitation assays detected either or both antibodies (seropositivity) in 41.9% of subjects with type 1 diabetes. GADab was detected in 36.6% and IA-2ab in 23.7% of type 1 diabetics. Prevalence of IA-2ab showed a reduction in frequency with disease duration (P = 0.026). In clinical type 2 diabetics, seropositivity was 10.0% with higher frequency in Malays (17.5%) than Chinese (9.7%) and Indians (4.5%). Multivariate analysis revealed that low fasting C-peptide was associated with seropositivity (odds ratio (OR) = 0.15; 95% confidence interval (CI) = 0.04-0.58). A significant relationship (OR = 13.5; 95% CI = 5.0-36.7) between insulin requirement and duration (>5 years) was also revealed. In patients with type 2 diabetes there was a trend of gradual progression to insulin dependency. However, there was considerable variation in body mass index between ethnic subgroups of type 2 diabetics, particularly for Chinese (mean (SD) = 26.0 (4.7)) and Malays (mean (SD) = 29.2 (5.9); P < 0.001).

Conclusions: Presence of both antibodies in our mixed ethnic group of type 1 diabetes patients was much lower than in Caucasians. Significant numbers of patients were seronegative for antibodies. Influences due to ethnicity and adiposity would require further investigations.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Asian Continental Ancestry Group
  • Autoantibodies / blood*
  • Biomarkers / blood*
  • Body Mass Index
  • C-Peptide / blood
  • China / ethnology
  • Diabetes Mellitus, Type 1 / immunology*
  • Diabetes Mellitus, Type 2 / immunology
  • European Continental Ancestry Group
  • Female
  • Glutamate Decarboxylase / immunology*
  • Humans
  • India / ethnology
  • Insulin / administration & dosage
  • Malaysia / ethnology
  • Male
  • Prevalence
  • Radioimmunoassay
  • Singapore

Substances

  • Autoantibodies
  • Biomarkers
  • C-Peptide
  • ICA512 autoantibody
  • Insulin
  • Glutamate Decarboxylase