What Are the Different Types of Insulin?
Insulin is the hormone normally made in the pancreas that stimulates the flow of sugar – glucose – from the blood into the cells of the body. Glucose provides the cells with the energy they need to function.
There are two main groups of insulins used in the treatment of diabetes: human insulins and analog insulins, made by recombinant DNA technology.
A milliliter is equal to a cubic centimeter. All insulin syringes are graduated to match this insulin concentration.
There are four categories of insulins depending on how quickly they start to work in the body after injection:
- Very rapid acting insulin,
- Regular, or Rapid acting insulins,
- Intermediate acting insulins,
- Long acting insulin.
In addition, some insulins are marketed mixed together in different proportions to provide both rapid and long acting effects. Certain insulins can also be mixed together in the same syringe immediately prior to injection.
Rapid Acting Insulins
A very rapid acting form of insulin called Lispro insulin is marketed under the trade name of Humalog.
A second form of very rapid acting insulin is called Aspart and is marketed under the trade name Novolog.
Humalog and Novolog are clear liquids that begin to work 10 minutes after injection and peak at 1 hour after injection, lasting for 3-4 hours in the body.
However, most patients also need a longer-acting insulin to maintain good control of their blood sugar.
Humalog and Novolog can be mixed with NPH insulin and are used as “bolus” insulins to be given 15 minutes before a meal.
Note: Check blood sugar level before giving Humalog or Novalog.
Your doctor or diabetes educator will instruct you in determining your insulin dose based on your blood sugar reading and anticipated meals and exercise.
Always check the bottle before drawing up the insulin. If the solution is cloudy, discard the bottle.
- If you are mixing Humalog or Novalog with a longer-acting insulin, always draw up the Humalog or Novalog first to maintain the purity and clarity of the Humalog and Novalog solutions.
Another solution of insulin that acts rapidly is called “Regular” or “R” insulin. This insulin does not act as quickly as Humalog or Novalog.
Regular insulin is a clear, colorless liquid that begins to work 30 minutes after injection and peaks at 3-5 hours after injection. It lasts 6-10 hours in the body.
Regular insulin is usually given 30 minutes before a meal. It can also be mixed with in the same syringe with longer acting NPH insulin or given separately immediately after each other.
Note: Glargine cannot be mixed with it.
Regular insulin is the most stable of all the different types of insulin. Unopened regular insulin is best refrigerated.
Always check the bottle before drawing up the insulin.
If the solution is cloudy, discard the bottle.
If you are mixing Regular with a longer-acting insulin, always draw up the Regular insulin first to maintain the purity and clarity of the Regular solution.
Examples of intermediate acting insulins are NPH.
Intermediate acting insulins are cloudy suspensions of crystalline insulin that need to be gently rotated between the hands before being used.
They begin to work 1 hour after injection and peak at 6-12 hours after injection. They last for 20-24 hours in the body. Intermediate insulins are often given before breakfast or they may also be given at bedtime, depending on your blood glucose reading. They can be mixed in the same syringe with Regular, Lispro and Aspart insulins.
Ultralente insulin is a long-acting insulin. Ultralente insulin is a cloudy suspension that begins to work 2-8 hours after injection and peak at about 12 hours. They last for around 8-24 hours in the body.
Ultralente insulin is often given before breakfast or before dinner in the evenings, or at bedtime, depending upon the doctor’s instructions. It can be mixed in the same syringe with regular insulin and when unopened, it is best stored in the refrigerator.
Another long-acting insulin is called Glargine insulin. It is an insulin analog manufactured by recombinant DNA technology.
Unlike other long-acting insulins, Glargine insulin is a clear solution of insulin that begins to work around 1 hour after injection without a pronounced peak. Small amounts of Glargine insulin are released slowly to provide a relatively constant amount of insulin in the body over 24 hours.
Note: Glargine insulin cannot be mixed with any other insulins.
A change to Glargine from NPH insulins should be done under the close supervision of a medical team.
There are three stable, premixed formulations of insulin:
- One contains 70% of NPH insulin and 30% of Regular insulin.
- Another formulation contains 50% of NPH and 30% of Regular insulin.
- The third contains 75% of NPH and 25% of Humalog.
These mixtures begin to work around 30 minutes after injection and peak in 2-8 hours. It lasts up to 24 hours in the body. As these premixed insulins contain rapid or very rapid acting insulin, they should be taken before meals as directed by your medical team.
With your doctor’s instructions, several combinations of two different kinds of insulin can be mixed together in the same syringe and given as one injection.
Once mixed, the combined injection must be given immediately or the effect of the regular component of the injection will be diminished.
The rapid-acting insulins, Lispro, Aspart and Regular, can be mixed with the longer acting NPH insulin.
Glargine cannot be mixed with any other insulin.