Comparative study of insulin antibodies in diabetic patients with primary insulin-dependence (type I) and secondary insulin-dependence (type II).

Insulin antibodies (% binding) were determined by RIA method in 404 insulin-treated diabetic patients divided into two groups: (A) primary insulin-dependent patients (Type I diabetes): 300 cases, 170 M, 130 F, mean age +/- SD 29.2 +/- 7.5 yrs, disease and insulin treatment duration 7.7 +/- 6 yrs: (B) Type II diabetic patients needing insulin (secondary insulin-dependence): 104 cases, 47 M, 57 F, aged 53.4 +/- 9.2 yrs, duration of diabetes 13.1 +/- 8.3 yrs, and of insulin treatment 3.1 +/- 2.1 yrs. Both groups of patients were with the same types of insulin preparations. In 297 cases, all belonging to group (A), fasting C-peptide was also determined. The titre of insulin antibodies was significantly (p less than 0.001) higher in patients with secondary insulin dependence than in those with primary insulin dependence (22.96 +/- 15.1% vs 10.25 +/- 9.89) in spite of the longer duration of insulin treatment in the later group; the mean C-peptide value found in 58 Type I diabetic patients with a binding capacity less than 10% was significantly lower (p less than 0.001) than that found in 11 Type I diabetic cases with a binding capacity greater than 20% (0.091 +/- 0.57 vs 0.273 +/- 0.37 pmol/ml); no correlation was found between insulin antibodies and metabolic control, insulin requirements or chronic complications.