Medical preparations of<unk> are never just<unk> in water (with nothing else). Clinical<unk>  are mixtures of<unk> plus other substances including preservatives. These prevent the protein from spoiling or denaturing too rapidly, delay absorption of the<unk>  adjust the pH of the solution to reduce reactions at the injection site, and so on. Slight variations of the human<unk> molecule are called<unk> analogues, (technically<unk> receptor ligands") so named because they are not technically<unk>  rather they are analogues which retain the hormone's glucose management functionality. They have absorption and activity characteristics not currently possible with subcutaneously injected<unk> proper. They are either absorbed rapidly in an attempt to mimic real beta cell<unk> (as with<unk> lispro,<unk> aspart, and<unk> glulisine), or steadily absorbed after injection instead of having a 'peak' followed by a more or less rapid decline in<unk> action (as with<unk> detemir and<unk> glargine), all while retaining<unk> s glucose-lowering action in the human body. However, a number of meta-analyses, including those done by the Cochrane Collaboration in 2005, Germany's Institute for Quality and Cost Effectiveness in the Health Care Sector IQWiG released in 2007, and the Canadian Agency for Drugs and Technology in Health (CADTH) also released in 2007 have shown no unequivocal advantages in clinical use of<unk> analogues over more conventional<unk> types. Choosing<unk> type and dosage/timing should be done by an experienced medical professional working closely with people who are diabetic . The commonly used types of<unk> are as follows. Fast-acting Includes the<unk> analogues aspart, lispro, and glulisine. These begin to work within 5 to 15 minutes and are active for 3 to 4 hours. Most<unk>  form hexamers, which delay entry into the blood in active form; these analog<unk>  do not but have normal<unk> activity. Newer varieties are now pending regulatory approval in the U.S. which are designed to work rapidly, but retain the same genetic structure as regular human<unk>  Short-acting Includes regular<unk>  which begins working within 30 minutes and is active about 5 to 8 hours. Intermediate-acting Includes NPH<unk>  which begins working in 1 to 3 hours and is active for 16 to 24 hours. Long-acting Includes the analogues glargine U100 and detemir, each of which begins working within 1 to 2 hours and continues to be active, without major peaks or dips, for about 24 hours, although this varies in many individuals. Ultra-long acting Includes the analogues<unk> glargine U300 and degludec, which begin working within 30 to 90 minutes and continues to be active for greater than 24 hours. Combination<unk> products Includes a combination of either fast-acting or short-acting<unk> with a longer acting<unk>  typically an NPH<unk>  The combination products begin to work with the shorter acting<unk> (5–15 minutes for fast-acting, and 30 minutes for short acting), and remain active for 16 to 24 hours. There are several variations with different proportions of the mixed<unk>  (e.g. Novolog Mix 70/30 contains 70% aspart protamine akin to NPH, and 30% aspart.)
Insulin 
Regular insulin
Pulsatile insulin
Lente insulin
Proglucagon
Ultralente insulin
Glucuronide
Glucagon 