insulin can cause side effects. The most important side effect that can occur with insulin is low blood sugar levels, although other problems are also possible. It is important to understand how to recognize and deal with the possible side effects of insulin.
Allergic reaction.it can be moderate or even severe.Moderate symptoms include swelling,itchy or squeezing at injection place.Severe symptoms among other are,pulse become quickly,blood pressure descends,squeezing all over the body,breath become difficult.if patient experiences the severe symptoms,he/she should immediately contact his/her doctor.