Insulin given intranasally induces hypoglycaemia in normal and diabetic subjects

Regular or crystalline insulin with sodium glycocholate as surfactant administered intranasally to normal volunteers induced hypoglycaemia and an increase in serum immunoreactive insulin concentrations. Serum C-peptide concentrations decreased or remained unchanged. Insulin administered intravenously to three of these subjects yielded a potency ratio of 1:8 for intranasal and intravenous insulin. In four insulin-dependent diabetics a cross-over study was performed on different days, insulin being administered once intranasally and once subcutaneously in a ratio of 1:9. In these patients the intranasal insulin was more effective than the subcutaneous insulin in preventing hyperglycaemia after breakfast. In four other insulin-dependent diabetics 11-hour monitoring was performed twice on two different days, insulin being administered in divided dosage sufficient to achieve a reasonable glycaemic profile. The average control was similar with the two routes of administration during the morning, whereas subcutaneous insulin was more effective than intranasal during the afternoon.