Diabetes Care, Vol 18, Issue 9 1225-1232, Copyright © 1995 by American Diabetes Association
Phospholipid and glutamic acid decarboxylase autoantibodies in diabetic neuropathy
AI Vinik, SB Leichter, GL Pittenger, KB Stansberry, MT Holland, AC Powers and S Suwanwalaikorn
Diabetes Institutes, Eastern Virginia Medical School, Norfolk, Virginia, USA.
OBJECTIVE: To determine the prevalence and significance of phospholipid
autoantibodies (PLAs) and glutamic acid decarboxylase (GAD) autoantibodies
in the circulation of normal patients and diabetic patients with and
without neuropathy. RESEARCH DESIGN AND METHODS: We measured PLAs in a
total of 78 patients (a diabetic group with somatic or autonomic neuropathy
[n = 40] another group without neuropathy [n = 38]), and GAD autoantibodies
in a subset of 22 patients. RESULTS: PLAs are found in 2% of the general
population. We found PLAs in 32% of the diabetic population without
neuropathy, in 88% of those with neuropathy, in 55% of those with
retinopathy, and in 25% of those with established nephropathy. The
frequencies of immunoglobulins in the neuropathic group were: IgG = 78%,
IgM = 33%, and IgA = 23%. There was no correlation between PLAs and
microalbuminuria, macrovascular disease, fibrinogen, duration of diabetes,
or neuropathy, but there was a strong correlation with total neuropathy
score. Sera with high PLA IgG titers bound to the surface of neuroblastoma
cells and inhibited cell growth. Antibodies to GAD65 were present in 32%
and to GAD67 in 0% of patients. No titers of GAD65, GAD67, or the GAD65
ratio were associated with the degree of neuropathy of the presence of
PLAs. CONCLUSIONS: PLAs occur frequently in the sera of patients with
diabetes and correlate with the extent of neuropathy, suggesting a role for
PLAs in the etiology thereof. The measurement of PLAs may constitute a
marker for ongoing damage to nerves.