Changing from porcine to human insulin.

The development of hypoglycaemia unawareness is associated with long duration of diabetes, improved glycaemic control, alcohol intake and recurrent hypoglycaemia. However, current evidence suggests that neither frequency of severe episodes nor mortality from hypoglycaemia are increased following a change from animal to human insulin. Nevertheless, a small number of patients continue to report an alteration in the nature of hypoglycaemic warning symptoms following a change in insulin species. This is possibly a consequence of a reduced catecholamine response to lowering blood glucose levels or to species differences in the effect of insulin on central nervous system function. In practical terms, it seems sensible to warn patients that the nature of the symptoms associated with hypoglycaemia might alter following conversion from porcine to human insulin. At the time of the changeover, patients should be encouraged to perform frequent blood glucose measurements. Also, the usual insulin dose should be reduced by 10% at the start of human insulin treatment. Other aspects of insulin treatment including injection technique, meal timing, exercise, etc. should be discussed. For patients who are convinced that loss of warning of hypoglycaemia occurred after conversion from porcine to human insulin, a change back to animal insulin would be preferred to relaxing glycaemic control in the first instance. Pressure should be brought to bear on the pharmaceutical industry to maintain the availability of animal insulins for the small number of patients who have experienced problems with human insulin.