There is increasing evidence to suggest that insulin-dependent diabetes mellitus is connected with autoimmunity. Antibodies to pancreatic islet cells were detected by indirect immunofluorescence in highest prevalence in insulin-dependent diabetics. That this antibody was complement fixing and of the IgG class has been reported by Bottazzo and Lendrum. The 125I-C1q binding test for detecting soluble immune complexes in native unheated human serum has been modified by Zubler. This radiolabeled C1q binding test has high sensitivity and reproducibility among the various methods proposed for detecting immune complexes. The method was applied to the study of sera from 52 child patients (3-15 yr old) with insulin-dependent diabetes mellitus. The 125I-C1q binding activity (C1q BA) for the 52 sera, 9.47±2.58%, was significantly higher than the value of 6.94±2.57% for normal controls (p<0.005). Slightly higher values were seen in 3 patients with positive anti-DNA-antibodies. 125I-C1q binding was not significantly increased in patients with positive antithyroid antibodies and insulin antibodies.
For the purpose of administrating insulin rectally, an insulin suppository was prepared by pestling porcine crystalline insulin with corn oil and surfactant (polyoxyethylene-9-laurylether). The final concentrations of insulin and surfactant were set at 10-50 U/kg and 2-4 w/w%, respectively. In normal dogs, a significant increase in mean plasma immunoreactive insulin concentration (IRI) (64, 88, 115μU/ml) was observed at 15 min after administration of the insulin suppository (2, 3 and 5 U/kg body weight, respectively), followed by a significant decrease in plasma glucose level (36, 38, 56%, respectively). Following suppository administration to depancreatized dogs at a dose of 5 U/kg, the mean peak IRI was 167μU/ml at 30 min, which was significantly higher than that in normal dogs (p<0.05, n=5). The main features of the insulin suppository so prepared were: 1) even at a dose of 2 U/kg by rectal administration, a marked increase in IRI was observed, and 2) insulin was absorbed more rapidly from the rectum than when injected intramuscularly. It was also shown that insulin is absorbed from the rectum to a greater extent in severe diabetic dogs than in normal dogs.