Insulin resistance versus dysregulation—a distinction without a difference

Summary For the last 10 years, the term ‘insulin dysregulation’ has replaced ‘insulin resistance’ when referring to horses with hyperinsulinaemia. The rationale was that this was an all‐inclusive term that covered all possible causes of hyperinsulinaemia. The implication is that hyperinsulinaemia has been shown to occur outside of insulin resistance; with insulin resistance being defined as failure of the insulin‐sensitive cells to respond normally to insulin, as best documented by the euglycaemic hyperinsulinaemic clamp. This article will show the evidence for that is weak to nonexistent in the horse and the term ‘insulin dysregulation’ is a misnomer that should be abandoned.