ISLET-CELL ANTIBODIES ARE ASSOCIATED WITH BETA-CELL FAILURE ALSO IN OBESE ADULT-ONSET DIABETIC-PATIENTS

To clarify the utility of islet cell antibodies (ICA) to correctly classify and predict insulin treatment in newly diagnosed diabetic subjects, ICA, body mass index (BMI), glycated hemoglobin (HbA(1c)), and fasting plasma C-peptide values were evaluated at and 3 years after diagnosis in 233 new, consecutively diagnosed, adult diabetic patients classified as obese or nonobese (National Diabetes Data Group, NDDG criteria). Among the 233 patients, 31 were nonobese ICA-positive (mean age at diagnosis 43+/-3 years), 55 nonobese ICA-negative (mean age at diagnosis 58+/-2 years), 7 obese ICA-positive (mean age at diagnosis 57+/-5 years), and 139 obese ICA-negative (mean age at diagnosis 58+/-1 years). Fasting C-peptide decreased (P<0.05) in nonobese ICA-positive patients who after 3 years showed lower BMI (22.6+/-0.6 versus 24.5+/-0.4; P<0.05), lower fasting C-peptide (0.14+/-0.06 nmol/l versus 0.71+/-0.07 nmol/l; P<0.001), and higher frequency of insulin treatment [28/31 (90%) versus 6/45 (13%); P<0.001] than nonobese ICA-negative patients. In obese ICA-positive patients, fasting C-peptide also decreased (Delta C-peptide 0.17+/-0.04 nmol/l; P<0.05) after diagnosis, and 3 years after diagnosis, obese ICA-positive patients showed lower BMI (25.7+/-1.2 versus 29.8+/-0.4; P<0.01) and fasting C-peptide (0.08+/-0.04 nmol/l versus 1.06+/-0.05 nmol/l; P<0.001) and higher HbA(1c) values (9.92%+/-0.68% versus 7.39%+/- .21%; P<0.01) and a higher frequency of insulin treatment [7/7 (100%) versus 5/121 (4%); P<0.001] than obese ICA-negative patients. Therefore, ICA detected at diagnosis of diabetes in both obese and nonobese adult patients indicate beta-cell dysfunction, high HbA(1c) levels, and progression to insulin dependency.