Insulin Basics

Insulin is a hormone produced by the pancreas.  It acts like a key to open cells in the body so they can receive glucose or sugar from the blood.  Without insulin, cells cannot get the glucose they need for energy and unused glucose builds up in the blood, resulting in diabetes.

Over 23 million people in the United States have diabetes.  Of those, approximately 13 percent take a combination of insulin and oral medications and another 14 percent just take insulin.  Here are some things you should know about insulin if you have insulin-dependent diabetes.

Insulin Characteristics
There are three general characteristics that distinguish between the many types of insulin:

  • Onset – This describes how long it takes after insulin is injected before it starts working to lower blood sugar levels.
  • Peak time – This shows the time after insulin is injected when it is most effective at reducing glucose.
  • Duration – This is the total time the insulin works to reduce glucose.  Once insulin is injected, it builds to a peak then gradually loses effectiveness until it is gone.  This total cycle is known as the duration.

Your doctor will develop a schedule for your insulin based on the characteristics of the medication prescribed.  It is important to understand that insulin types are not interchangeable because the characteristics can be very different. Rapid-acting insulin peaks very quickly and has a short duration.  Long-acting insulin peaks slowly and lasts up to a full day.  Some people need a combination of two or more types of insulin to effectively control their blood glucose. 

Insulin Doses
Insulin is sold as a solution which means it is dissolved or mixed with a liquid.  In the United States, the most common solution strength is U-100 which means there are 100 units of insulin in each milliliter of fluid.  Other countries use different standard solutions.  For example the standard solution in Europe and Latin America is U40 which has 40 units per milliliter.  If you travel to other countries, be sure to note the dosage on any insulin you obtain and make sure you are using the correct amount in the correct size syringe to match your prescribed dose.

Insulin must be injected into the fat under the skin.  It cannot be taken as an oral medication because it will not survive the process of digestion to get into the blood.  All types of insulin can be injected with a syringe and needle.  Some insulin is also available in cartridges which are injected by an insulin pen.  Insulin pumps contain a reservoir of rapid-acting insulin which is injected at a constant, low rate to maintain an even base level in the blood. Before eating, more insulin can be given as a bolus to balance carbohydrates in the meal.

Additives in Insulin
All insulin is mixed with other ingredients to prevent bacteria from growing and to help keep the insulin safe.  Long-acting insulin also contains extra ingredients to give it the ability to last longer.  Although it is rare, some people are allergic to the additives in intermediate and long-acting insulin. 

Insulin Sources
All insulin sold in the United States today is synthetic human insulin which is created in a laboratory.  At one time, all insulin was made from the pancreases of pigs or cows. Some people are allergic to animal insulin and cannot use it.  Others find that they can control their blood glucose more effectively with animal insulin than with synthetic.  Animal insulin is no longer made in the United States.  However, the U.S. Food and Drug Administration (FDA) does allow individuals to import animal insulin from other countries for their own personal use.

Denise DeWitt is a freelance writer for


Sources: The 4 Types of Insulin and Their Potential Side Effects. Web. February 27, 2012.,,20189208,00.html Type 2 Diabetes. Insulin Reference Chart. Debra Manzella, RN. Web. February 27, 2012.

Medical News Today. Diabetes Treatment – taking insulin. Web. February 27, 2012.

eHow Health. Types of Insulin. Web. February 27, 2012.

American Diabetes Association. Insulin Basics. Web. February 27, 2012.

Tags: Characteristics of insulin,insulin characteristics,insulin doses,insulin strengths,insulin additives,insulin allergy,insulin duration,insulin onset,insulin peak,animal insulin

Category: Featured Articles,Resources