Little is known about the prevalence and significance of islet cell immunity in elderly patients with type 2 diabetes. The low antibody titers against islet-cell antigens in LADA elderly patients may be a sign of a less aggressive autoimmune diabetes.
The objective: To establish the changing frequency and titers of GADA and IAA in elderly diabetics.
Material: 83(56F;27M)diabetic patients (6091 y) divided in age related groups. Group 1: 55 (36F;19M) patients (6069 y). Group 2: 14 (9F;5M) pts (7079). Group 3: 14 (11F;3M) pts (8091). Mean duration of diabetes 5.6±6.4 y.
Method: GADA and IAA determined by RIA (ANTI-INSULIN RIA and GAD-AB kits), (CIS). IAA estimated in patients not treated with insulin. The positive GADA and IAA titers were over 1 U/ml and 5.5%B/T.
Results: Group 1: Positive GADA were found in 13(27%) assays, 5(10.2%) patients with the level 7.164.5 U/ml and 8(16.5%) subjects 1.022.1 U/ml. In 11(22.9%)patients GADA titers 0.380.98 U/ml were found (method sensitivity>0.3 U/ml). The positive IAA were in 20(40.8%) assays (5.613.2%B/T). Group 2: In 3(21.5%) patients, the GADA were >1 U/ml (1.63; 38.5;68.5 U/ml). 4(28.6%) patients had GADA 0.930.99 U/ml. The positive IAA were obtained in 4(28.6%) patients (9.119.7%B/T). Group 3: There were positive GADA in 4(30.8%)assays (1.312.1 U/ml). In 8(61.5%%) patients GADA ranged 0.611.42 U/ml. In 6(42.9%) subjects the positive IAA was obtained (1 patient 36.1%B/T and the rest 5.66.95%B/T).
Summary: The percentage of patients with high GADA titer didnt significantly change with the age. In the older patients the frequency of GADA low titers (close to 1 U/ml) clearly increased. The IAA frequency and titer didnt significantly change with the age.
Conclusion: Eldery diabetic patients are characterized by increasing frequency of GADA sublimited titers as they aged. The autoantibodies low level may signify a less aggressive beta-cell autoimmunity as well as instability of the immunological system related to aging or both.