Abstract
A 45-year-old man was diagnosed as having type-2 diabetes mellitus in 2005. Glimepiride and insulin therapy with premixed insulin lispro 25/75 was initiated in June 2010, and combination therapy with PEG-interferon α-2b and ribavirin for chronic hepatitis C was started in July 2010. The patient exhibited an allergic reaction at the injection site in November 2010, during the administration of interferon therapy. This symptom persisted after changing the type of insulin, and the patient's glycemic control began to worsen in association with deteriorating fasting plasma glucose and HbA1c levels (NGSP value) , which increased to 264 mg/dl and 10.0 %, respectively. The patient was admitted in March 2011. Marked elevation of specific IgE antibodies against human insulin was observed. A skin test for allergies was positive for both human insulin and human recombinant insulin. The patient was diagnosed with an immediate-type allergy to insulin. The laboratory data also showed a high titer of insulin antibodies in the serum. We changed the treatment regimen to glimepiride and liraglutide after discontinuing the insulin analogue therapy. Thereafter, the allergic reaction in the skin disappeared and the patient's glycemic control gradually improved simultaneously with a reduction in the titer of insulin antibodies in the serum. The development of autoimmune diseases, such as type 1 diabetes, has been reported to be a side effect of treatment with interferon; however, few cases of immediate-type allergies to insulin have been documented. This is a rare case of insulin antibody-positive type 2 diabetes mellitus with an insulin allergy that developed during interferon therapy.
