November 25, 2015
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Diabetes Treatment (cont.)

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Different methods of delivering insulin

Not only is the variety of insulin preparations growing, so are the methods for administering insulin.

Pre-filled insulin pens

In the twentieth century, insulin was available only in an injectable form that required carrying syringes (which were made of glass and required sterilization just a few decades ago), needles, vials of insulin, and alcohol swabs. Clearly, patients found it difficult to take multiple shots each day; as a result, good blood sugar control was often compromised. Many pharmaceutical companies now offer discreet and convenient methods for delivering insulin.

Many manufacturers offer pen delivery systems. Such systems resemble the ink cartridge in a fountain pen. A small, pen-sized device holds an insulin cartridge (usually containing 300 units). Cartridges are available for the most widely used insulin formulations. The amount of insulin to be injected is dialed in, by turning the bottom of the pen until the required number of units is seen in the dose-viewing window. The tip of the pen consists of a needle that is replaced with each injection. A release mechanism allows the needle to penetrate just under the skin and deliver the required amount of insulin. The cartridges and needles are disposed of when finished and new ones simply are inserted. In some systems, the entire pen is disposed. These insulin delivery devices are less cumbersome than traditional methods.

Insulin pumps

Over the past 20 years, dramatic advances in insulin delivery have improved insulin pumps. An insulin pump is composed of a reservoir similar to that of an insulin cartridge, a battery-operated pump, and a computer chip that allows the user to control the exact amount of insulin being delivered. Current pumps on the market are about the size of a pager or beeper. The pump is attached to a thin plastic tube (an infusion set) that has a cannula (like a needle but soft) at the end through which insulin passes. This cannula is inserted under the skin, usually on the abdomen. The cannula is changed every two days. The tubing can be disconnected from the pump while showering or swimming. The pump continuously delivers insulin, 24 hours a day. The amount of insulin is programmed and is administered at a constant rate (basal rate). Often, the amount of insulin needed over the course of 24 hours varies, depending on factors like exercise, activity level, and sleep. The insulin pump allows the user to program many different basal rates to allow for variations in lifestyle. The user can also program the pump to deliver additional insulin during meals, covering the excess demands for insulin caused by eating carbohydrates.

Insulin pumps enable tight blood sugar control and support lifestyle flexibility, while minimizing the effects of low blood sugar (hypoglycemia). At present, the pump is the closest device on the market to an artificial pancreas. The latest pumps do not require tubing. The insulin delivery device is placed directly on the skin and any adjustments needed for insulin delivery are made through a PDA-like device that must be kept within a 6-foot range of the insulin delivery device (and can be worn in a pocket, kept in a purse, or on a tabletop when working).

The most exciting innovation in pump technology has been the ability to combine the pump in tandem with newer glucose sensing technology. Glucose sensors have improved dramatically in the last few years and are an option for patients to gain further insight into their patterns of glucose response to tailor a more individual treatment regimen. The newest generation of sensors allows for a real-time glucose value to be given to the patient. The implantable sensor communicates wirelessly with a pager-sized device that has a screen. The device is kept in proximity to the sensor to allow for transfer of data; however, it can be a few feet away and still receive transmitted information. Depending on the model, the screen displays the blood glucose reading, a thread of readings over time, and a potential rate of change in the glucose values. Sensors can be programmed to produce a "beep" if blood sugars are in a range that is selected as too high or too low. Some can provide a warning beep if the drop in blood sugar is occurring too quickly.

To take things one step further, there is one particular sensor that is new to the market that is designed to communicate directly with the insulin pump. While the pump does not yet respond directly to information from the sensor, it "requests" a response from the patient if there is a need for adjustments according to the patterns it has been programmed to detect. The ultimate goal of this technology is to "close the loop" by continuously sensing what the body needs, then responding with the appropriate insulin dose.

Inhaled insulin

Inhaled insulin was approved by the FDA and marketed by Pfizer in 2006 as Exubera. Exubera was poorly accepted after marketing and was subsequently discontinued during October 2007.

Intranasal or transdermal insulin

Other routes for the delivery of insulin have been tried. Intranasal insulin delivery was initially promising; however, this approach was associated with poor absorption and nasal irritation. Transdermal insulin delivery (via skin patch) yielded disappointing results. Insulin in pill form is ineffective since digestive enzymes in the gut break it down. Surprisingly, oral insulin is being tested in a major clinical trial by TrialNet as a potential intervention to prevent type 1 diabetes in those at high risk of progressing from to overt type 1 diabetes.

Medically Reviewed by a Doctor on 5/7/2015


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