Islet cell autoantibody levels after the diagnosis of young adult diabetic patients.
OBJECTIVE
The aim was to determine the course of islet cell antibodies [glutamate decarboxylase (GADA), tyrosine phosphatase-like islet antigen 2 (IA-2A) and islet cell (ICA)] after the diagnosis of the diabetic patient.


METHODS
The Diabetes Incidence Study in Sweden (DISS) attempted to prospectively enrol all newly diagnosed diabetic patients aged 15-34 years during 1992 and 1993. C-peptide and autoantibody levels were determined from venous blood samples at diagnosis and again at yearly intervals for 6 years.


RESULTS
After the first year, the odds of remaining GADA positive decreased by 9% per year [odds ratio (OR) = 0.91, 95% confidence interval (CI) = 0.85-0.96] while the mean GADA index remained unchanged ( = 0.8, P = 0.37). There was no change in the percentage of subjects testing IA-2A positive after the first year ( = 0.1, P = 0.75). However, the mean index decreased 0.04 per year (95% CI: 0.03-0.05)-a 7.9% decline (95% CI: 5.4-10.4%). The odds of a subject testing positive for ICA decreased by 24% per year (OR = 0.76, 95% CI = 0.70-0.82). The mean ICA levels decreased 0.75 per year (95% CI: 0.66-0.84)-a 16.4% decline (95% CI: 14.1-18.6%). The rate of change in titres for all three autoantibodies was independent of gender, human leucocyte antigen genotype and C-peptide status.


CONCLUSIONS
GADA levels remained high while ICA levels declined. In contrast to a previous study, we found that the proportion of IA-2A subjects remaining positive did not decrease after the first year, while the average index decreased slightly.
Jensen
R
R
Department of Biostatistics, University of Washington Medical Center, Seattle, WA 98195, USA. richaj@u.washington.edu
Gilliam
L
L
Torn
C
C
Landin-Olsson
M
M
Palmer
J
J
Akesson
K
K
Kockum
I
I
Lernmark
B
B
Karlsson
A F
AF
Lynch
K F
KF
Breslow
N
N
Lernmark
A
A
Sundkvist
G
G
D000293:Adolescent; D000328:Adult; D001323:Autoantibodies / Q000378:metabolism*; D002096:C-Peptide / Q000097:blood; D003922:Diabetes Mellitus, Type 1 / Q000097:blood / Q000175:diagnosis* / Q000188:drug therapy; D005260:Female; D005968:Glutamate Decarboxylase / Q000276:immunology*; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D016017:Odds Ratio; D011237:Predictive Value of Tests; D011446:Prospective Studies
D001323:Autoantibodies; D002096:C-Peptide; C096322:ICA512 autoantibody; C024211:islet cell antibody; D005968:Glutamate Decarboxylase