Insulin detemir is a long-acting type of insulin. Insulin is one of many hormones that help the body turn the food we eat into energy. This is done by using the glucose (sugar) in the blood as quick energy. Also, insulin helps us store energy that we can use later. When you have diabetes mellitus (sugar diabetes), your body cannot make enough insulin or does not use insulin properly. So, you must take additional insulin to regulate your blood sugar and keep your body healthy. This is very important as too much sugar in your blood can be harmful to your health.