Insulin edema is a rare complication of insulin therapy which has been described in known or newly diagnosed people with diabetes, following initiation or intensification of insulin treatment. Here we present a 63-year-old man with complaints of weight gain, shortness of breath, and lower extremity edema starting two weeks after the change of his insulin pump to the hybrid closed-loop insulin pump system and substitution of U-100 aspart insulin with U-500 regular insulin. The gene discussed is INS; the disease is diabetes mellitus.