Controversies in the use of insulin analogues.

INTRODUCTION In recent years, insulin analogues have been developed in order to improve the pharmacological parameters of insulin and to better mimic endogenous insulin output. Given that some of the modifications introduced into insulin analogues are located in a domain involved in a potential interaction with the insulin-like growth factor-I receptor (IGF-IR), it has been postulated that certain analogues may display IGF-I-like activities. AREAS COVERED We review the recent literature investigating the risk of malignant neoplasms and mortality in diabetic patients treated either with human insulin or with one of three insulin analogues (lispro, aspart, and glargine). We examine how critical analyses are consistent with the notion that the use of insulin glargine is associated with a possible increased risk of tumors in humans. EXPERT OPINION The introduction of insulin analogues has had a major impact in diabetes care. However, the benefit of some of these new insulins for the patient has yet to be demonstrated. Furthermore, research is needed to clarify whether insulin glargine is more strongly associated with cancer risk compared with other insulins.