MON-566 - Insulin Desensitization and Omalizumab Use during Pregnancy in A Patient with Diabetes Mellitus and Severe Insulin Allergy

Introduction

Insulin allergy is a rare but challenging complication in patients with diabetes, particularly during pregnancy when glycemic control is critical for maternal and fetal outcomes, and insulin therapy is often unavoidable. We report the case of a pregnant patient with diabetes who developed severe insulin-induced anaphylaxis, successfully treated with omalizumab and insulin desensitization.

Case Description

A 44-year-old woman at 9 weeks gestation with a history of diabetes, developed an anaphylactic reaction following insulin administration.

In prior pregnancies, she required high-dose insulin (detemir 120 U twice daily and lispro 50–60 U three times daily). Before conception, she achieved excellent glycemic control on tirzepatide and metformin (A1c 4.8%); tirzepatide was discontinued during preconception planning. After pregnancy confirmation, she was started on insulin degludec and lispro with continuous glucose monitoring (CGM). She initially experienced pruritus after injections, followed weeks later by anaphylaxis after lispro, requiring emergency treatment.

Following her anaphylactic episode, a multidisciplinary approach was initiated in coordination with the endocrinology and allergy teams. Testing showed elevated insulin-specific IgE (6.34 kU/L). Intradermal skin tests were positive for insulin degludec, lispro, aspart, regular, and glargine. She underwent insulin degludec desensitization (23 U) at 10 weeks gestation and started omalizumab 300 mg every 28 days. Despite partial tolerance, pregnancy glycemic goals remained unmet on insulin degludec, metformin, and glyburide with CGM data showing fasting hypoglycemia and postprandial hyperglycemia.

At 30 weeks gestation, she underwent insulin aspart desensitization in the intensive care unit (ICU) using a subcutaneous dose-escalation protocol (up to 20 U over 2 hours), which was well tolerated. She was subsequently maintained on degludec and aspart, uptitrated until she met pregnancy glycemic goals. Metformin was reintroduced and glyburide discontinued. She delivered via scheduled cesarean section at 36 weeks for fetal macrosomia. Postpartum, glycemic control improved, insulin was discontinued, and glycemic control was maintained on metformin alone.

Discussion / Conclusion

Insulin allergy during pregnancy presents complex management challenges. Desensitization, performed in a closely monitored setting, such as the ICU, allows for safe insulin reintroduction when alternatives are limited. The use of omalizumab can serve as an adjunct to reduce IgE-mediated hypersensitivity and facilitate safe insulin desensitization in a highly sensitized patient. This case underscores the value of multidisciplinary care, individualized desensitization strategies, and vigilant maternal-fetal monitoring to optimize outcomes.

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