Everyone with type 1 diabetes must take insulin—either by injection or with an insulin pump—because their pancreas no longer produces this essential hormone that helps regulate the amount of glucose in the blood. Without insulin, they would not survive! Many people with type 2 diabetes also must take insulin to supplement what their pancreas makes.
What is glucose?
Glucose is a simple sugar found in the foods we eat. After we eat food with carbohydrate and it is broken down and digested, glucose travels into the bloodstream and then into all the millions of cells in our body, where it provides those cells with energy. How does the glucose get into each cell? Well, that’s where insulin comes in. Insulin has the crucial job of helping move the glucose molecules from the bloodstream into all the cells of our body; it thereby helps to lower our blood glucose levels.
In persons who don’t have diabetes, the pancreas delivers just the right amount of insulin into the bloodstream at all times necessary, to keep our blood glucose levels even. In those with diabetes, however, insulin doses must be balanced with the foods we eat and our activity level so that a safe blood glucose level results, one that’s not too high and not too low.
In earlier days, when medical science first discovered that insulin was needed to control diabetes, the hormone was extracted from pig and cow pancreas. Today, insulin is made from human DNA in the laboratory. This means that quite a few different types of insulin are now available, and they differ as to their actions once they’re inside the body.
Types of insulin
- Rapid-acting insulin (Novalog, Humalog, Apidra) is a clear liquid type of the hormone. It starts working in 15 minutes after being injected, peaks in 1 to 2 hours, and remains active for a total of 2 to 4 hours in all.
- Always eat within 15 minutes of injecting rapid-acting insulin so as to reduce the risk of low blood glucose.
- Fast-acting insulin (Regular), another clear type, starts working in 30 minutes, peaks in 2 to 4 hours, and remains active for a total of 5 to 7 hours in all.
- You may need a morning snack to reduce your risk of low blood glucose if you inject fast-acting insulin before breakfast.
- Intermediate insulin (NPH) starts working in 1 to 2 hours, peaks in 4 to 12 hours, and remains active for a total of 24 hours. This type of insulin is cloudy.
- Long-acting insulin (Lantus, Levemir) is clear. It starts working in 3 to 4 hours, doesn’t usually peak, and remains active for a total of 20 to 24 hours. It should be given at about the same time each day.
- Combination insulin contains both a rapid- or fast-acting insulin plus an intermediate or long-acting insulin. It can be used to reduce the number of injections necessary each day. It is cloudy.
Delivering the insulin
Insulin comes in glass vials or in easy-to-carry insulin pens. A vial holds 1,000 units of insulin. A pen has a cartridge that holds 300 units. Insulin can also be delivered by syringes, which come in different sizes and can hold from 30 units of insulin to 100 units. The needles used in the syringes and in the pens come in different lengths: 6 millimeters (mm), 8 mm, and 12 mm.
Your doctor determines your insulin dose based on your blood glucose readings, your eating habits and activity level, and your weight. Insulin doses do not have to stay the same; they should be adjusted as needed. Always talk to your doctor if you continue to have high blood glucose readings or if you have frequent or a severe low blood glucose level.