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). 

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• 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

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.