Insulin Therapy - Types

Types

Medical preparations of insulin (from the major suppliers – Eli Lilly, Novo Nordisk, and Sanofi Aventis – or from any other) are never just 'insulin in water'. Clinical insulins are specially prepared mixtures of insulin plus other substances including preservatives. These delay absorption of the insulin, adjust the pH of the solution to reduce reactions at the injection site, and so on.

Slight variations of the human insulin molecule are called insulin analogues, (technically "insulin receptor ligands") so named because they are not technically insulin, rather they are analogues which retain the hormone's glucose management functionality. They have absorption and activity characteristics not currently possible with subcutaneously injected insulin proper. They are either absorbed rapidly in an attempt to mimic real beta cell insulin (as with Lilly's lispro, Novo Nordisk's aspart and Sanofi Aventis' glulisine), or steadily absorbed after injection instead of having a 'peak' followed by a more or less rapid decline in insulin action (as with Novo Nordisk's version Insulin detemir and Sanofi Aventis's Insulin glargine), all while retaining insulin's glucose-lowering action in the human body. However, a number of meta-analyses, including those done by the Cochrane Collaboration in the United Kingdom in 2002, Germany's Institute for Quality and Cost Effectiveness in the Health Care Sector 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 insulin analogues over more conventional insulin types.

Choosing insulin type and dosage/timing should be done by an experienced medical professional working closely with the diabetic patient.

The commonly used types of insulin are:

• Fast-acting: Includes the insulin analogues aspart, lispro, and glulisine. These begin to work within 5 to 15 minutes and are active for 3 to 4 hours. Most insulins form hexamers which delay entry into the blood in active form; these analog insulins do not, but have normal insulin 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 insulin.
• Short-acting: Includes regular insulin which begins working within 30 minutes and is active about 5 to 8 hours.
• Intermediate-acting: Includes NPH insulin which begins working in 1 to 3 hours and is active 16 to 24 hours.
• Long acting: Includes the analogues glargine and detemir, each of which begins working within 1 to 2 hours and continue to be active, without major peaks or dips, for about 24 hours, although this varies in many individuals.
• Ultra-long acting: Currently only includes the analogue degludec, which begins working within 30–90 minutes, and continues to be active for greater than 24 hours.
• Combination insulin products – Includes a combination of either fast-acting or short-acting insulin with a longer acting insulin, typically an NPH insulin. The combination products begin to work with the shorter acting insulin (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 insulins (e.g. Novolog Mix 70/30 contains 70% aspart protamine, and 30% aspart.)