Diabetic ketoacidosis in a patient taking alpelisib for breast cancer: A case report.

Published Date: 01st February 2026

Publication Authors: Anwar. MB, Michaels. S, Taylor. J, Caton. K, Murphy. S, Bujawansa. S, Sullivan. H, Aung. ET

Conference Abstract:

A 65-year-old female with metastatic breast cancer presented with weight loss, nausea and vomiting. Five weeks ago, she was commenced on alpelisib. She had type 2 diabetes treated with sitagliptin 100 mg and dapagliflozin 10 mg. HbA1c 45 mmol/mol 6 months before the admission. Investigations on admission showed glucose 14.9 mmol/L, ketones 7 mmol/L, pH 7.245, HCO3 12.2 mmol/L, lactate 0.7 mmol/L, Na 126 mmol/L, K 4.7 mmol/L and normal inflammatory markers. She was treated as per DKA protocol. Dapagliflozin and sitagliptin were discontinued. She was then switched to basal-bolus insulin regimen. Oncology team decided to continue with Alpelisib. She was discharged with a diabetic clinic follow-up and plan to switch to oral diabetic medications later.
Discussion(s): Diabetic ketoacidosis is an uncommon side effect of alpelisib. Hyperglycaemia occurs early during treatment (median time of onset about 2 weeks from initiation of therapy). Inhibition of PI3K-alpha blocks the metabolic actions of insulin and creates a transient insulin resistance state. Blood glucose levels usually normalise within 1 week of treatment withdrawal. Metformin is a standard treatment for alpelisib-induced hyperglycaemia. Insulin therapy is not normally required due to short half-life of alpelisib and hyperglycaemia resolve with stopping alpelisib. However, insulin is considered in uncontrolled hyperglycaemia, ketoacidosis, failure of non-insulin antihyperglycaemic therapy or concomitant acute illness. Learning Points: 1. Patients receiving alpelisib should have a hyperglycaemic risk assessment before starting treatment. If hyperglycaemia is managed properly, most patients should be able to continue alpelisib without dose adjustment or interruption.

Anwar, M.B.; Michaels, S.; Taylor, J.; Caton, K.; Murphy, S.; Westall, S.J.; , S.; Sullivan, H.; Aung, E.T. (2025). Diabetic ketoacidosis in a patient taking alpelisib for breast cancer: A case report. Diabetic Medicine. 42(Supp 1) [Online]. Available at: https://dx.doi.org/10.1111/dme.15498 [Accessed 4 February 2026].