Types of insulin

The following types of insulin products differ in terms of how quickly they start working and how long their effect lasts, and their chemical structure:

• Short-acting insulin:
  Insulin analogues:
  Start working: about 5 to 10 minutes after injection
  Maximum effect: about 1 to 1.5 hours after injection
  Duration of effect: about 2 to 3 hours
  Regular insulins (human insulin, porcine insulin, bovine insulin):
  Start working: after about 15 to 30 minutes
  Maximum effect: about 1.5 to 3 hours after injection
  Duration of effect: about 4 to 8 hours
• Intermediate-acting insulin (insulin analogues, human insulin or porcine insulin with delayed action due to addition of NPH (neutral protamine Hagedorn) or zinc):
  Start working: about 2 hours after injection
  Maximum effect: about 4 to 6 hours after injection
  Duration of effect: about 12 to 14 hours
• Long-acting insulin (insulin analogues, human insulin, porcine insulin):
  Start working: slowly
  Maximum effect: depends on the way in which the action is delayed
  Duration of effect: usually up to 24 hours
• Premixed insulin (insulin analogues, human insulin, porcine insulin):
  A standard mixture of short-acting insulin and intermediate-acting or long-acting insulin.

Short-acting insulin (such as regular insulin, insulin analogues or premixed insulin) is normally injected before meals. Some people wait a certain amount of time following the injection before they eat. Others vary the time interval between injecting and eating depending on their blood sugar levels.

Many people find fixed injection-meal intervals bothersome and difficult to stick to in everyday life. So far there is no evidence to show that blood sugar levels are better controlled if you stick to fixed injection-meal intervals.

Compared to human insulin, insulin analogues start lowering blood sugar somewhat sooner after being injected. It is not clear whether this has any health benefits. But research hasn't found any evidence that it does.

If, for instance, a particular type of insulin were shown to prevent complications caused by poorly controlled blood sugar levels, that type of insulin would offer a clear advantage. It would also be an advantage if the insulin prevented strong fluctuations in blood sugar levels that lead to noticeably low or high blood sugar (hypoglycemia or hyperglycemia). Or if it made it easier for people to follow their daily treatment plan. But studies in this area suggest that insulin analogues and human insulin are equally good in the treatment of diabetes.