Insulin glargine (brand name Lantus[1]) is a long-acting insulin manufactured by Sanofi Aventis. It is dosed once or twice a day in two equal doses, and is available in a vial or in a cartridge for use with the OptiClik pen. Lantus has an acidic pH, and cannot be mixed with other insulins. Lantus was the first clear long-acting insulin. Some users find that Lantus does not last for a full 24 hours or lasts for longer than 24 hours and works best when divided into two doses twelve hours apart.