Infrequent response by diabetic rats to insulin-liposomes.

1. Insulin-liposomes of four different lipid combinations were given intragastrically to normal rats on twenty occasions and to diabetic rats on 164 occasions. 2. Normal rats showed no hypoglycaemic response to either sonicated or unsonicated liposomes. 3. Diabetic rats failed to respond to sonicated liposomes but six animals became hypoglycaemic on two occasions each after administration of unsonicated insulin-liposomes. 4. The responsive animals had all been diabetic for more than 18 days but another thirty-seven similar animals were unresponsive. 5. It is suggested that insulin-liposomes may facilitate insulin absorption in certain limited circumstances but that previous reports have been over enthusiastic.