Combinations of beta cell specific autoantibodies at diagnosis of diabetesin young adults reflects different courses of beta cell damage

To explore the natural course of beta cell function in recent onset diabete s, a subgroup (n = 157) of all incident cases (n = 879) 15-34 years old. 19 92-1993 in Sweden. and with positivity for at least one autoantibody of isl et cell antibodies (ICA), glutamic acid decarboxylase antibodies (GADA) or tyrosine phosphatase antibodies (1A-2A) were followed prospectively thr the first four years with annual analysis of C-peptide. The aim was to relate the course of beta cell function, measured as C-peptide, in early diabetes with the presence of different islet autoantibodies at diagnosis. We found that patients positive for ICA alone (n = 11 ) had significantly higher C-p eptide levels both at diagnosis and during the first three years compared w ith the other patients (n = 146; p = 0.022, p < 0.001, p = 0.004 and p = 0. 0022). Patients positive for GADA alone or in combination with other antibo dies (n = 125) had significantly lower C-peptide during the first three yea rs after diagnosis compared with the other patients (n = 32. p < 0.001, p = 0.0011 and p = 0.0136). Patients with two or three autoantibodies had C-pe ptide levels similar to levels found in patients positive only for GADA. Ho wever. after four years, there were no significant differences between any of the groups of different autoantibody combinations. At diagnosis. 55% (86 /157) of the patients had C-peptide: levels above the lower normal range of 0.25 nmol/l, but the frequency of patients with beta cell Function above t his level decreased after two years to 41% (65/157; p = 0.035) and after fo ur years to 22% (35/157; p = 0.0041).