Type 1 diabetes is an autoimmune disease. The body's immune system attacks the cells that make insulin. As a result, the body makes very little insulin, or no insulin. Type 1 diabetes is also called insulin-dependent diabetes. It often happens at a younger age. It often starts before age 30. Treatment for type 1 diabetes includes getting daily multiple injections of insulin or using an insulin pump.
Type 2 diabetes typically means the body can't use insulin correctly. This is called insulin resistance. Treatment often begins with making changes in your lifestyle to help lower your blood sugar levels. This includes diet, exercise, and weight loss. But if this treatment plan doesn't work, you may need medicine. Medicines for diabetes may be pills or insulin injections.
Insulin is a hormone made by the pancreas. It helps lower the level of sugar (glucose) in your blood. It does this by moving sugar from the blood into the body's cells. Once inside the cells, blood sugar becomes the body's main source of energy.
Insulin varies based on the onset, peak, and duration. Each works in certain ways.
How quickly the insulin starts to work after it is injected
The period of time when the insulin helps most to lower blood sugar levels
How long the insulin keeps working in the body
Insulin may act differently when given to different people. So the times of onset, peak time, and duration may be different. There are 4 main types of insulin:
Peak time (approximate)
Rapid-acting, Lispro, Aspart, Glulisine insulin
2 to 4 hours
Short-acting, Regular (R) insulin
2 to 3 hours
3 to 6 hours
Intermediate-acting, NPH (N) or Lente (L) insulin
4 to 12 hours
12 to 18 hours
Long-acting, Glargine, Detemir insulin
1 to several hours
Source: American Diabetes Association
Some people with diabetes may need to take 2 different types of insulin to control their blood sugar levels. Some insulin can be bought already mixed together. This includes Regular and NPH insulin. This lets you inject both types of insulin in one injection. Other types of insulin can't be mixed together. They may need 2 separate injections.
Insulin is made at different strengths. U-100 insulin (100 units of insulin per milliliter of fluid) is the most common strength. The syringes for giving insulin are different for each different strength. This means a U-100 syringe can be used only with U-100 insulin.
Recently, an inhaled form of insulin has become available. This is a form of rapid-acting insulin. An ultra-long-acting insulin has also been developed. This insulin begins to work in 30 to 90 minutes, does not peak, and lasts for over 40 hours.
The type of insulin chosen may reflect your choice and how well you are able to follow any given treatment. Other factors include:
If you have type 1 or type 2 diabetes
Your daily schedule of meals, work, and activity
How willing you are to check your blood sugar levels regularly
How much exercise you get each day
How well you understand diabetes
How stable your blood sugar levels are
Insulin has to enter the body's bloodstream to work. Insulin must be given by injection. It can't be taken by mouth, because it is broken down in the stomach during digestion. So to get it into the blood, it must be injected into the fat layer. This is often done in the arm, thigh, or belly. Different sites on the body allow the insulin to enter the blood at different rates. Insulin injected into the belly wall works the fastest. Injecting it into the thigh works the slowest.
The timing of insulin injections is very important.
Rapid-acting and short-acting insulin often needs to be given before meals. Or before sugar from a meal starts to enter the bloodstream.
Intermediate-acting insulin or mixed insulin needs to be taken at the same time every day along with a fixed eating schedule.
Long-acting insulin should be taken at the same time every day. But your meal times can be flexible.
Always talk with your healthcare provider about your own insulin treatment. He or she can tell you where to inject the insulin, how much to inject, and how often. Your provider can tell you the times of day you should take it. Bring your glucose testing results to your appointment. Your provider can help you make the adjustments needed in your insulin schedule and dosing.
Many types of insulin injection devices are available. Some examples of devices include:
The syringe is one of the most common devices used to give insulin. The needle of the syringe is used to draw insulin out of a bottle and then to inject it under the skin.
An insulin pen is like a preloaded syringe that can be used multiple times. It is often used for multiple, daily doses of insulin. The insulin pen holds a cartridge with insulin. The pen looks like a writing pen. It has a small needle that can be screwed on at the tip. A dial on the pen lets you set the right dose. A plunger on the other end of the pen is used to actually deliver or inject the insulin.
Insulin jet injector
An insulin jet injector looks like a large pen. The injector makes high-pressure air to "spray" the insulin through the skin.
External insulin pump
An insulin pump is a device that pumps insulin continuously through plastic tubing. The tubing is attached to a needle under the skin near the belly. It can also be used to inject a single, large dose (bolus) of insulin as needed. The pump is small enough to be worn on a belt or in a pocket.
Insulin is quickly broken down during digestion. So it has always been given by injection, often just under the skin. New pharmaceutical materials and methods are being developed to protect insulin from being broken down in the digestive tract. Researchers are looking at the best way to do this.
In type 1 diabetes, the pancreas makes too little insulin, or no insulin at all. Replacing a pancreas with part or all of a healthy transplanted pancreas would seem to be a cure for type 1 diabetes.
The first pancreas transplants were tried in the late 1960s. But it was not until the surgery methods improved and new medicines were developed years later that pancreas transplants became a realistic treatment for type 1 diabetes. Pancreas transplants are still studied at many centers in the U.S. and around the world. It is the standard treatment in certain cases.
When successful, a pancreas transplant cures diabetes. Or it at least reduces the number of severe episodes of low and high blood glucose. Blood sugar levels become normal because the new pancreas makes insulin. But as with most types of solid organ transplants, complications may happen. The most common complications include rejection of the new organ, infection, and harmful effects from anti-rejection medicines. These medicines must be taken for life after the transplant.
Pancreas transplants can be done in 3 ways:
Simultaneous pancreas and kidney transplant (SPK). Most people with type 1 diabetes who meet the criteria for pancreas transplant also have kidney disease. So surgeons often transplant both a pancreas and a kidney at the same time. This type of transplant has had the best success rates.
Pancreas after kidney transplant (PAK). A pancreas is transplanted into a person who has already been given a kidney transplant. This procedure generally has a success rate near that of SPK procedures.
Pancreas transplant alone (PTA). Only the pancreas is transplanted. This type of procedure is done less often. It generally has a lower success rate than the other procedures.
The islet cells in the pancreas make insulin. Only about 1 or 2 out of 100 of the cells in the pancreas are islet cells.
In the 1970s, research into islet cell transplants in mice was very successful. But transplants in people were not as successful. Researchers at the University of Alberta in Edmonton, Alberta, Canada, developed a special way of transplanting the islet cells that shows great promise. But research continues.
Islet cell transplants are considered a minor surgery. No cut (incision) is needed. Islet cells are taken from a donor pancreas and then injected into the recipient's liver through a long, thin tube (catheter). Once the islet cells have been implanted in the donor, they begin to make and release insulin. But the failure rates are high after the first year or 2. Islet cell transplants can also be done from a person's own pancreas. A person may be a candidate for this procedure if they have severe chronic pancreatitis, and some of the insulin-producing cells are still active.
People who get an islet cell transplant must take anti-rejection medicine. This protects the transplanted islets from being rejected and destroyed by the body’s normal immune system.
Check with your insurance company to find out if blood glucose monitoring equipment and insulin pumps are covered under your plan. Medicare Part B covers the cost of insulin pumps and supplies if you meet certain requirements.