Levemir is a long-acting human insulin that is used to treat type 1 diabetes (condition in which the body does not produce insulin and therefore cannot control the amount of sugar in the blood). It is also used to treat people with type 2 diabetes (condition in which the body does not use insulin normally and, therefore, cannot control the amount of sugar in the blood) who need insulin to control their diabetes. Levemir comes as a solution (liquid) to inject subcutaneously (under the skin). It is usually injected once a day, with the evening meal or at bedtime.Sometimes Levemir may be injected twice a day, in the morning before breakfast and in the evening with the evening meal or at bedtime about 12 hours later. Some common side effects of Levemir include low blood sugar (hypoglycemia), reactions at the injection site (local allergic reaction) and weight gain.