[Cross-sectional study of the relation between carboxypeptidase-H antibody and islet beta cell function in patients with latent autoimmune diabetes in adults].
OBJECTIVE
To explore the relation between carboxypeptidase-H antibody (CPH-Ab) and islet beta cell function in patients with latent autoimmune diabetes in adults (LADA) and to further confirm the diagnostic value of CPH-Ab for LADA.


METHODS
Five hundred and forty-five patients who were initially diagnosed as Type 2 diabetes mellitus (T2DM) were tested with CPH-Ab and GAD-Ab by radioligand assay (RLA). T2DM patients, according to CPH-Ab and GAD-Ab status, were divided into CPH-Ab(+) group, GAD-Ab(+) group, and Ab(-) group to compare their islet beta cell function [represented by fasting C-peptide (FCP) and 2h postprandial C-peptide (2hCP)]. The relation between CPH-Ab and islet beta cell function in LADA was analyzed.


RESULTS
The fasting C-peptide level in CPH-Ab(+) patients was between that of GAD-Ab(+) patients and that of Ab(-) patients (P<0.05), and the difference was still significant when the 3 groups were stratified with duration of disease (All P<0.05), but not with body mess index (all P>0.05). Corrected by concomitant variables including age, age at onset, duration of disease, and sex, the differences among the 3 groups were statistically significant (both P<0.001). Among the 3 groups FCP was lower than Ab(-) group in CPH-Ab(+) (P<0.05) and both FCP and PCP were lower than Ab(-) group in GAD-Ab(+) group (P<0.05 and P<0.01). The proportions of patients with insulin deficiency in CPH-Ab(+), GAD-Ab(+), and Ab(-) group were 27.6% (8/29), 48.1% (8/52) and 13.5% (54/400), respectively, which were significantly different among the 3 groups (P<0.001). GAD-Ab, BMI, and fasting blood glucose had effects on FCP and PCP in T2DM patients (All P<0.05), while CPH-Ab did not enter the equation in multivariable stepwise regressive analysis (P>0.05).


CONCLUSIONS
The effect of CPH-Ab is less marked than that of GAD-Ab on islet beta-cell function in LADA patients. The value of CPH-Ab for the failure of islet beta-cell function in LADA should be determined prospectively.
Yang
Lin
L
Diabetes Center, Institute of Metabolism and Endocrinology, Second Xiangya Hospital, Central South University, Changsha 410011, China.
Zhou
Zhi-guang
ZG
Huang
Gan
G
Jin
Ping
P
Qi
Hai-ying
HY
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001323:Autoantibodies / Q000097:blood*; D043423:Carboxypeptidase H / Q000276:immunology*; D003430:Cross-Sectional Studies; D003922:Diabetes Mellitus, Type 1 / Q000097:blood / Q000175:diagnosis / Q000276:immunology*; D005260:Female; D006801:Humans; D050417:Insulin-Secreting Cells / Q000502:physiology*; D008297:Male; D008875:Middle Aged
D001323:Autoantibodies; D043423:Carboxypeptidase H