Unless you take insulin you probably never think about the different types and most people who take it don’t know that there is more than one concentration. But it’s true, not only are there different types of insulins, there are different strengths.
Most insulin in the United States is U100. That means that there are 100 units of insulin in every milliliter (ml) (or cubic centimeter) of liquid. A bottle of insulin has 10 ml of liquid; therefore a bottle of u100 insulin contains 1000 units of insulin (100 units of insulin x 10 ml of liquid).
U100 insulin is given in an U100 syringe of which there are three sizes: 1/3 cc, ½ cc and 1 cc. A 1/3 cc syringe holds 30 units of insulin, ½cc hold 50 units and 1 cc holds 100 units. The type of syringe you use depends on how much insulin you need to take at one time.
But there are two other insulin strengths available. One is called U40 and the other is U500. U40 is not readily available in the United States for use in people. It is used in Europe and Latin America and also for pets. (Yes, unfortunately our pets are getting fatter and developing type 2 diabetes at an alarming rate.) A bottle of U40 contains 40 units of insulin in every 100 ml of liquid. A bottle of U40 would have 400 units of insulin total.
U500 insulin, which used to be given to people only rarely, is experiencing a prescription explosion because of the rise in obesity. Used for people who need very large amounts of insulin, either because they are extremely obese or because they are very insulin resistant for other reasons, such as happen when people take large doses of steroids.
With five times the strength of U100, it is formidable insulin that causes severe hypoglycemia if not used correctly. Like regular insulin it needs to be taken 30 minutes before a meal. It peaks between 2-4 hours later and can last up to 10 hours. There are a variety of dosing schedules available, although U500 is often given 3 to 4 times a day to mimic the action of both basal and bolus insulin in one. It can also be given in addition to oral agents or meal time insulin as a basal insulin
Finally U100 insulin sometimes needs to be diluted to accommodate the very small amounts of insulin needed for infants. Parents will be instructed to dilute U100 insulin down to U50 or even U10 to avoid the possibility of inducing hypoglycemia in infants.
It is best to use a syringe to match the type of insulin you are using. In the case of U40 insulin, there are U40 syringes available. While there isn’t a specific syringe available for U500 or diluted insulin, you can use syringes designed for use with other insulins, with some modifications. .
With a little manipulation, it is possible to use a U100 syringe with any concentration of insulin. The table below shows the marking level you would fill a U100 syringe to for a variety of insulin concentrations to get 10 units of insulin.
Patients using U500 usually have a choice of using tuberculosis (TB) syringe or the U100 syringe. To make the dose transparent to the patient, the physician will often list the dose in the number of units the patient will fill in the syringe. For example his instructions to you may be to take 5 units of U500. You will fill the syringe to the fifth marking without having to make any conversions. He will know that you are getting the equivalent of 25 units of insulin; however, Patients taking U500 should be counseled to always indicate that they are using U500 insulin when going to other health providers’ offices or to the hospital.
It is also important for patients to contact their providers for help in adjusting their insulin as excessive U500 can lead to severe hypoglycemia. And, as usual, don’t make any changes to your self-management routine before talking with your health care provider.