Human ultralente, which is considered to be a long-acting insulin, is absorbed at different rates in different people. Pre-mixed insulins are convenient for those who draw up a mixture of NPH and regular in one syringe. The most typical mixture is 70 percent NPH and 30 percent regular. Pre-mixed insulin can be helpful for people who have trouble drawing up insulin out of two different bottles and reading the correct directions and dosages. It's also useful for those who have poor eyesight or dexterity and is a convenience for people whose diabetes has been stabilized on this combination.
All insulins come dissolved or suspended in liquids, but the solutions have different strengths.
The most commonly used strength in the United States today is U-100. That means it has 100 units of insulin per milliliter of fluid. Not used in this country, but still used in Europe and Latin America, is U-40, which has 40 units of insulin per milliliter of liquid. As you may know, different insulin strengths call for different syringes. While this mismatching isn't too likely to occur when you buy all your products in the United States, it is something to watch for when you are traveling in other countries.