Background: Everolimus is an orally administered anti-cancer drug that inhibits the mammalian target of rapamycin (mTOR) signal transduction route. Use of everolimus may be associated with insulin resistance, manifesting in impaired glucose tolerance or hyperglycaemia.
Case description: A 74-year-old female patient with a locally recurrent breast cancer developed hyperglycaemia, which started 2 weeks after the initiation of treatment with everolimus 10 mg once daily. Metformin and insulin were administered to restore normoglycaemia.
Conclusion: At the initiation of treatment with an mTOR inhibitor such as everolimus the treating physician should be aware of the occurrence of hyperglycaemia. Metformin is then the medicine of first choice.