Is it safe to acutely discontinue insulin therapy in patients with chronic hyperglycaemia starting GLP-1R agonists?

We report two patients with chronic hyperglycaemia secondary to type 2 diabetes who developed severe vomiting on d. The first patient was diagnosed with a mixed picture of diabetic ketoacidosis (DKA) and hyperosmolar hyperglycaemic state (HHS) and the second, with DKA. They were on insulin therapy which was discontinued on commencing d because of inefficacy and weight gain. The HHS patient developed dehydration secondary to vomiting and had lactic acidosis but no other precipitant could be found in either case. It appears that the abrupt insulin discontinuation coupled with vomiting and dehydration led to the metabolic derangements. Subsequent C-peptide levels were found to be low in both patients. In view of the predisposition of patients with chronic hyperglycaemia to glucagon-like peptide 1 receptor (GLP-1R) downregulation and the lag time to optimal efficacy of GLP-1R agonists, we propose that patients should have C-peptide levels measured to determine the risk of ketosis and whether insulin should be continued with dose adjustments when starting a GLP-1R agonist.