Insulin is normally secreted in our body and when this secretion is inadequate, we top it up with external insulin injections and this is not harmful. Insulin administration brings about good control of blood sugars thereby delaying the onset of diabetes related complications. Insulin injections are essential during certain situations like very high blood sugars, pregnancy or post-surgery where it is temporary and can be stopped afterwards. Sometimes it may be the only choice in people who fail to respond effectively to oral anti-diabetic medicines. Also, in people with type 1 diabetes life-long insulin therapy is essential.