Insulin glargine, sold under the brand name Lantus among others, is a long-acting modified form of medical insulin, used in the management of type I and type II diabetes. It is typically the recommended long acting insulin in the United Kingdom. It is injected just under the skin. Effects generally begin an hour after use. Common side effects include low blood sugar, problems at the site of injection, itchiness, and weight gain. Other serious side effects include low blood potassium. NPH insulin rather than insulin glargine is generally preferred in pregnancy. After injection microcrystals slowly release insulin for about 24 hours. This insulin causes body tissues to absorb glucose from the blood and decreases glucose production by the liver. Insulin glargine was approved for medical use in the United States in 2000. It is on the World Health Organization's List of Essential Medicines. In 2020, it was the 32nd most commonly prescribed medication in the United States with more than 17million prescriptions. In July 2021, the US Food and Drug Administration (FDA) approved an interchangeable biosimilar insulin product called Semglee (insulin glargine-yfgn) for the treatment of diabetes. Medical uses The long-acting insulin class, which includes insulin glargine, do not appear much better than neutral protamine Hagedorn (NPH) insulin, but do have a greater cost, making them, as of 2010, not cost effective for the treatment of type 2 diabetes. In a previous review it was unclear if there is a difference in hypoglycemia, as there was not enough data to determine any differences with respect to long term outcomes, however a more recent Cochrane systematic review did not find clinically significant difference when comparing insulin glargine to NHP insulin, insulin detemir or insulin degludec in the management of type I Diabetes in neither adults or children in periods of 6 months or longer. It is not typically the recommended long acting insulin in the United Kingdom. Semglee is indicated to improve glycemic control in adults and children with Type 1 diabetes and in adults with Type 2 diabetes. Semglee is both biosimilar to, and interchangeable with (can be substituted for), its reference product Lantus (insulin glargine), a long-acting insulin analog. Mixing with other insulins Unlike some other longer-acting insulins, glargine must not be diluted or mixed with other insulin or solution in the same syringe. However, this restriction has been questioned. Adverse effects Common side effects include low blood sugar,