Severe insulin resistance associated with subcutaneous amyloid deposition.

A 59-year-old man with type 1 diabetes mellitus presented with severe resistance to subcutaneously injected insulin. Histological analysis of the injection sites, demonstrated foreign body type granulomas surrounding areas of amyloidosis. It is suggested that the granulomas were the source of an insulin-degrading enzyme (IDE) which simultaneously degraded amyloidogenic precursors into localized amyloid deposits. These findings may add insight into the role of insulin-degrading enzymes in the etiology of subcutaneous insulin resistance syndromes.