A case report of insulin edema associated with insulin icodec

Insulin edema is a rare complication that may occur after the initiation of insulin therapy. Although it usually resolves promptly after discontinuation of insulin, severe cases can lead to pulmonary edema, congestive heart failure, and acute renal failure. Insulin icodec is a recently marketed once-weekly, long-acting basal insulin, and its clinical use is increasing in Japan because it offers the convenience of once-weekly administration with an acceptable safety profile. In this report, we describe what is, to our knowledge, the first case of edema associated with insulin icodec. An 82-year-old man with glucocorticoid-induced diabetes mellitus in the setting of pre-existing impaired glucose metabolism was started on insulin icodec because of worsening glycemic control and developed bilateral leg edema a few days after the first injection. As he had no signs of heart failure, liver disease, or renal impairment, insulin icodec-induced edema was suspected, and insulin icodec was discontinued. Notably, it took more than one month after discontinuation of insulin icodec for the edema to improve. This case suggests that, compared with edema caused by conventional insulin preparations, insulin icodec-associated edema may show a delayed course of resolution. A closer and longer observation should be considered when initiating insulin icodec, particularly in insulin-naive people or in those with suboptimal glycemic management.