Also called: Insulin Dosing Methods
The ability to correctly self-administer doses of insulin is crucial to the long-term health of many people with diabetes. Insulin is a hormone necessary to process glucose (blood sugar), the body’s main source of energy.
All people with type 1 diabetes, and some with type 2 diabetes or other forms of diabetes, require insulin therapy. For many years, patients only had one method of insulin delivery – a syringe with a needle injected under the skin. This remains the chief form of insulin delivery in use today.
However, several alternatives to the needle and syringe have emerged, including:
- Insulin pumps
- Insulin pens
- A pod-like device that adheres to the skin
- Insulin jet injectors
- Implantable insulin pumps
Inhaled insulin powder became available in 2006, but, citing poor sales, the company that marketed the drug announced after little more than a year that it would stop selling it. Other forms of inhaled insulin are under development, and additional methods being investigated include insulin patches and pills.
People who take insulin should discuss the various delivery options with their physician. Not every method is an option for every individual. Once a method of insulin administration has been selected, a physician can provide crucial advice about how best to self-administer the medication.
About insulin administration
Many people with diabetes need to take insulin medications to control their glucose (blood sugar). There are several options for administering these drugs, but the most popular is still the needle and syringe.
No matter the method of injection, the injection site affects how quickly the medication is absorbed into the body. Patients need to vary their injection sites to prevent damage to tissues.
Insulin is absorbed the most quickly when injected into the abdomen. Other sites often used for injections include the arms, thighs or buttocks. Patients should be sure to choose an injection site that is at least a half-inch away from the site of their previous injection.
Insulin can be delivered:
- Under the skin (subcutaneous). This is the most common way to deliver insulin into the bloodstream.
- Into a vein (intravenous). This is the quickest way to deliver insulin into the bloodstream.
- Into the muscle (intramuscular). This is the second-quickest way to deliver insulin into the bloodstream.
- By mouth (oral). Researchers have developed inhalers that deliver insulin powder through the mouth and then to the lungs for absorption. The first available inhaled insulin, however, was discontinued for commercial reasons in 2007 after little more than a year.
Patients injecting insulin should be sure to thoroughly clean the skin at the injection site to prevent infection. Insulin should be delivered at an angle suggested by a physician. This is usually between 45 and 90 degrees and depends on the thickness of a patient’s skin.
Adaptive equipment is available to help patients with visual or motor difficulties use insulin-delivery devices. Patients should consult their physician to ensure that they are properly administering their medication.
Recent research suggests that many diabetic individuals, particularly those not yet prescribed insulin, would risk their health to avoid insulin injections and that some physicians are reluctant to prescribe the medication to patients who would benefit from it. Improved methods of insulin administration may address these issues.
Other options for people with insulin-dependent diabetes may include a pancreas transplant or an islet cell transplant.
Types and differences
For many years, needle and syringe was the only method patients had for administering insulin. It remains the most popular form of delivery.
A variation of this method called basal/bolus insulin administration offers people with diabetes greater flexibility in meal planning.
However, alternative insulin-delivery methods have emerged. The various options provide an array of choices for people with diabetes, with each method appealing to different patients based on their preferences and the specific nature of their disease. These alternative delivery methods include:
- Insulin pumps. A lightweight device about the size of a cell phone holds insulin that flows through a tube and needle inserted into the patient’s abdomen. The patient wears this device day and night, occasionally removing it for activities such as athletics or showering. Insulin pumps continuously deliver basal doses of insulin to control glucose (blood sugar). The pump also allows the patient to release bolus doses of insulin as needed.
Patients who use insulin pumps have to take an active role in managing their care. They must commit to glucose monitoring several times a day and keeping a close watch on carbohydrate consumption.
A recent innovation is a small pod-like device with an adhesive bottom that adheres to the skin. It delivers the insulin through a short, thin tube (cannula) and is replaced after a few days. The wireless unit is remotely controlled with a handheld gadget, similar to a personal digital assistant (PDA), that incorporates a glucose monitor.
Surgically implantable insulin pumps are also being developed.
- Insulin pens. These devices resemble fountain pens and use a cartridge of insulin. Patients turn a dial to set the dosage and press a plunger to deliver the medicine, usually in the abdomen, upper arms, thighs or buttocks.
It is important that patients using insulin pens ensure that they properly mix the insulin before injecting the medication. Recent research indicates that many patients are not properly mixing their dosages, which results in insulin that is absorbed too quickly. This increases the chance of episodes of low glucose (hypoglycemia).
- Insulin jet injectors. A high-pressure mechanism sends a fine spray of insulin through the skin. No needles are involved, but some patients find the high-pressure air to be painful.
- Inhaled insulin powder. An inhaler delivers the insulin through the mouth. The medication travels to the lungs, where it is absorbed into the bloodstream. The first brand of inhaled insulin, Exubera, became available to patients in July 2006. The U.S. Food and Drug Administration (FDA) described it as the biggest advance in insulin therapy since discovery of the hormone in the 1920s, but sales fell far short of expectations. The company that marketed Exubera announced in October 2007 that it would stop selling the drug in three months. It suggested that physicians begin moving their patients to other medications. The company that actually developed Exubera said it might seek another marketing partner so that the drug could remain available, but acknowledged obstacles including high costs.
Clinical trials involving about 2,500 people with diabetes found inhaled insulin to be safe and effective. The FDA approved the medication for adults who have type 1 diabetes or type 2 diabetes. Some people, including anyone with type 1 diabetes, still needed to inject long-acting insulin.
People who smoke, recently quit smoking or have asthma, bronchitis or emphysema were not to use this form of insulin. Annual lung function tests were advised. The American Diabetes Association expressed optimism that inhaled insulin may increase compliance but concern that it may have long-term effects on the lungs.
- Insulin infusers (also called subcutaneous infusion sets). A small tube called a catheter is inserted through the skin and can be kept in place for several days. The medication is injected through the catheter instead of through the skin.
- Chronic intermittent intravenous insulin therapy (CIIIT). This investigational treatment supplements daily subcutaneous injections with high-dose intravenous insulin. CIIIT is typically performed at an outpatient clinic once a week for several hours. The purpose of CIIIT is to reduce hypoglycemia and other complications. It might be an option for patients with conditions such as uncontrolled diabetes or hypoglycemia unawareness.
Leading Insulin Delivery Systems
|Needle and syringe||Injection||Inexpensive; insulins can be mixed||Less convenient than some other methods; needles make some patients uncomfortable|
|Insulin pump||Automatic release via battery-run pump||Insulin delivered easily; fewer needle sticks||Expensive; frequent glucose testing is necessary|
|Insulin pen||Injection||Convenient and discreet storage and delivery||Not available for all insulin types|
|Insulin jet injector||High-pressure air||No needles involved||Cost; some patients find high-pressure air painful; some medication does not penetrate skin|
In addition, several other potential forms of insulin administration may be available in the future. Methods being assessed include:
- Insulin sprays. These may be administered through the nose or through the mouth. As with inhaled insulin powder, large amounts may be required to be effective, which increases the expense of the therapy. One oral insulin spray is available in Ecuador and has received regulatory approval in India, according to its manufacturer.
- Other forms of oral insulin. Development of insulin pills has lagged because the medication is digested in the stomach and does not reach the bloodstream. Scientists are trying to overcome that obstacle and are investigating other oral methods, including drops, chewing gum, liquid insulin that is swished in the mouth and insulin that is placed under the tongue or between the cheek and gums.
- Insulin patch. A continuous, low dose of insulin is delivered through these patches, which are placed on the skin, like nicotine patches used by people trying to quit smoking. The biggest drawback with this method is that insulin is a larger molecule than nicotine and does not penetrate the skin easily.
- Artificial pancreas. This surgically implanted device would combine an insulin pump and a glucose sensor. It may one day free diabetic individuals from having to adjust their insulin medication themselves.
Basal/bolus insulin administration
Basal/bolus insulin administration is a variation on the traditional needle-and-syringe delivery method. It is also known as multiple daily injections (MDI) or the “poor man’s pump.” This method involves several daily injections of fast-acting insulin at mealtimes (the bolus doses) accompanied by one or more daily injections of long-acting insulin (the basal doses).
This method is used to control glucose (blood sugar) levels similar to the use of insulin pumps but at a fraction of the cost. As with pump delivery, the basal/bolus method allows patients greater flexibility in meal planning. In addition, the basal/bolus method can reduce the number of insulin reactions a patient suffers due to a mismatch between peak effect of insulin in the body and meal planning.
Basal/bolus administration is also effective for obtaining tight control of glucose levels. This method may be beneficial for women trying to bring their diabetes under control before pregnancy.
Though basal/bolus insulin administration offers some advantages to patients, it can also be somewhat difficult to learn. Patients need practice in learning to deliver the right amount of bolus insulin based on the amount of food in a meal. Patients also need to check their glucose levels multiple times and give themselves multiple injections each day. Finally, weight gain can be a side effect of basal/bolus administration.
Questions for your doctor
Preparing questions in advance can help patients have more meaningful discussions with their physicians regarding their conditions. Patients may wish to ask their doctor the following questions about insulin administration:
- Of the various methods of taking insulin, how do their advantages and disadvantages compare for me?
- Which method or methods of insulin administration do you recommend for me?
- Do you recommend any particular type or brand of this device for me?
- How might this method of insulin administration affect my diet or exercise habits?
- Will I need training from a diabetes educator in using this device?
- What insertion sites should I use, and how often should I rotate them?
- How often will I need to check my glucose?
- What plan should I have in place in case I have an insulin or glucose emergency?
- What are my options if I have trouble with this way of taking insulin?
- Are there any methods of insulin administration nearing approval that could benefit me?
- Could an islet cell transplant or a pancreas transplant be the answer for me?