HELP ON DIABETES

FAST-ACTING INSULIN PREPARATIONS

There are four fast-acting insulin preparations:

Regular insulin

Insulin lispro

Insulin aspart

Insulin glulisine

1) Regular Insulin

The following is true about regular insulin:

• Regular insulin has to be injected thirty minutes before a meal so that the insulin peak matches the glucose peak. However, this is inconvenient, and the advice is often ignored.  
• After injection, the rise in insulin level is not as rapid as might be desirable to match the glucose rise.  
• The duration of action is longer than desirable so that the insulin level remains a little high even after the glucose level has fallen, increasing the risk of hypo­gly cemia. Also, a larger dose of regular insulin lasts longer than a smaller dose.  
• Rubbing or warming the injection site (for example, by sitting in a hot tub) speeds up insulin absorption.  
• Insulin injected into the abdomen absorbs more rapidly than that injected in the upper arm, and absorption in the thigh is the slowest.  

For these reasons, scientists have modified the insulin molecule to create insulin analogs, which have more desirable absorption properties after subcutaneous injection. The three fast-acting insulin analogs are:   

2) Insulin lispro (brand name Humalog)

3) Insulin aspart (brand name Novolog)

4) Insulin glulisine (brand name Apidra)

These insulins get absorbed more quickly after injection, so that they can be injected within fifteen minutes of starting a meal. After injection, the peak insulin is twice as high as after regular insulin, without a significant delay. The site of injection also has less of an impact: the abdomen, upper arm, and thighs all have relatively similar absorption. Since these fast-acting analogs are absorbed faster, their effect lasts for a shorter period of time—about four hours (rather than six hours). These properties make these insulins more effective at controlling the glucose rise after meals. Clini­cal studies have shown that when these insulin analogs are used in an optimal man­ner, you can achieve improved glucose control with less risk of hypoglycemia.

However, there are some cautionary notes: first, because the peak level of the insu­lin with the analogs is higher after a meal, it is important for you to be more precise in counting the carbohydrates you are consuming. Regular insulin is more forgiving of errors in carbohydrate counting. Also, if you were to consume a very fatty meal, which delays glucose absorption, you have to inject these insulin analogs after a meal.