The prevalence of the 65-kilodalton isoform of glutamic acid decarboxylase autoantibodies by glucose tolerance status in elderly patients from the cardiovascular health study.
BACKGROUND
Autoantibodies (AA) to glutamic acid decarboxylase (GAD65), a determinant of risk for autoimmune diabetes, have been found in up to 10% of patients with type 2 diabetes. In older adults, this marker may also serve as a determinant of risk for autoimmune diabetes and enhance diabetes classification.


OBJECTIVE
The objective of this study was to evaluate the relationship between GAD65AA and glucose tolerance status, current diabetes treatment, and clinical measures in older adults.


METHODS
GAD65AA were measured at baseline in 3318 participants from the Cardiovascular Health Study, a cohort study of 5888 individuals 65 or older.


METHODS
The population-based cohort was recruited from four U.S. sites.


METHODS
Patients included all Cardiovascular Health Study participants with known diabetes, newly diagnosed diabetes, impaired fasting glucose, impaired glucose tolerance, and a sample of normal glucose-tolerant participants.


METHODS
GAD65AA, body mass index, fasting glucose and insulin levels, blood pressure, lipid levels, and diabetes treatment at baseline were measured.


RESULTS
The prevalence of GAD65AA increased with decreasing glucose tolerance in both Blacks (n = 560) and Whites (n = 2730), being more pronounced in known diabetic individuals. GAD65AA were found in 2.3, 5.8, 7.8, and 8.3% of diabetic participants, reporting use of no diabetes medication, oral hypoglycemic agents, insulin only, and both oral hypoglycemic agents and insulin, respectively (P = 0.02, linear trend). Among diabetic participants, GAD65AA positivity was associated with diabetes treatment, higher fasting glucose, and lower body mass index.


CONCLUSIONS
Even among older individuals with diabetes, GAD65AA may be a useful marker in identifying a subgroup of autoimmune diabetes, serve as a marker of insulin requirement, and remain stable over years.
Barinas-Mitchell
Emma
E
Department of Epidemiology, Graduate School of Public Health, University of Pittsburgh, 130 DeSoto Street, Pittsburgh, PA 15261, USA. barinas@edc.pitt.edu
Kuller
Lewis H
LH
Pietropaolo
Susan
S
Zhang
Ying-Jian
YJ
Henderson
Tyona
T
Pietropaolo
Massimo
M
D000368:Aged; D000375:Aging; D001323:Autoantibodies / Q000097:blood*; D001786:Blood Glucose / Q000032:analysis; D001794:Blood Pressure; D002318:Cardiovascular Diseases; D015331:Cohort Studies; D003924:Diabetes Mellitus, Type 2 / Q000201:enzymology / Q000276:immunology; D005215:Fasting; D005260:Female; D018149:Glucose Intolerance / Q000276:immunology*; D005968:Glutamate Decarboxylase / Q000276:immunology*; D006801:Humans; D007328:Insulin / Q000097:blood; D007527:Isoenzymes / Q000276:immunology*; D008055:Lipids / Q000097:blood; D016015:Logistic Models; D008297:Male; D009749:Nutrition Surveys
D001323:Autoantibodies; D001786:Blood Glucose; D007328:Insulin; D007527:Isoenzymes; D008055:Lipids; D005968:Glutamate Decarboxylase; C401141:glutamate decarboxylase 2