Multiple factors affect the loss of measurable C-peptide over 6 years in newly diagnosed 15- to 35-year-old diabetic subjects.
OBJECTIVE
The aim of this study is to identify risk factors for the loss of measurable plasma C-peptide in newly diagnosed 15- to 35-year-old diabetic subjects.


METHODS
This Swedish study included 778 subjects. C-peptide levels were obtained each year for 6 years after diagnosis. Loss of measurable C-peptide was defined as a level at or below the lower detection limit of the local assay (0.13 nmol/l). In addition to C-peptide, other baseline covariates included gender, age, body mass index, HLA genotype, and autoantibody levels.


RESULTS
Compared with autoantibody-negative subjects, autoantibody-positive subjects had lower median baseline C-peptide (0.27 vs. 0.50, P<.001), their levels declined over the study period, and the risk of losing measurable C-peptide was significantly higher when more than one autoantibody was present [odds ratio (OR), 4.0; 95% confidence interval (CI), 2.13-7.54]. Among autoantibody-positive individuals, the presence of GAD65Ab (OR, 1.8; 95% CI, 1.24-2.51) and islet cell antibodies (OR, 1.6; 95% CI, 1.19-2.18) conferred a higher risk for loss of measurable C-peptide as did female gender (OR, 1.6; 95% CI, 1.17-2.11) and time after diagnosis (OR, 1.5 for each additional year postdiagnosis; 95% CI, 1.41-1.57). Higher baseline C-peptide levels were protective (OR, 0.5 for each additional log(e) nanomoles per liter; 95% CI, 0.36-0.58).


CONCLUSIONS
This study identified autoantibody status, gender, and baseline C-peptide levels as factors that will be useful for predicting the disease course of 15- to 35-year-old diabetic individuals.
Jensen
Richard A
RA
Department of Biostatistics, University of Washington, Seattle, WA, USA. richaj@u.washington.edu
Gilliam
Lisa K
LK
Törn
Carina
C
Landin-Olsson
Mona
M
Karlsson
F Anders
FA
Palmer
Jerry P
JP
Kockum
Ingrid
I
Akesson
Karin
K
Lernmark
Barbro
B
Lynch
Kristian
K
Breslow
Norman
N
Lernmark
Ake
A
D000293:Adolescent; D000328:Adult; D001323:Autoantibodies / Q000276:immunology; D002096:C-Peptide / Q000097:blood* / Q000276:immunology; D003920:Diabetes Mellitus / Q000097:blood* / Q000175:diagnosis* / Q000453:epidemiology / Q000276:immunology; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D012307:Risk Factors; D013997:Time Factors
D001323:Autoantibodies; D002096:C-Peptide