Insulin pump

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Insulin pump, showing an infusion set loaded into spring-loaded insertion device. A reservoir is attached to the infusion set (shown here removed from the pump).
Filling an insulin pump reservoir. (Left to right) 1: Reservoir in sterile packaging. 2: Filling the reservoir. 3: Reservoir with needle and plunger removed, ready for attachment to infusion set.

An insulin pump is a medical device used for the administration of insulin in the treatment of diabetes mellitus, also known as continuous subcutaneous insulin infusion therapy. The device configuration may vary depending on design. A traditional pump includes:

Other configurations are possible. For instance, more recent models may include disposable or semi-disposable designs for the pumping mechanism and may eliminate tubing from the infusion set.

An insulin pump is an alternative to multiple daily injections of insulin by insulin syringes or an insulin pen and allows for intensive insulin therapy when used in conjunction with blood glucose monitoring and carb counting.

Dosing[edit]

Standard bolus.JPG
Extended bolus.JPG
Combo bolus.JPG
Super bolus.JPG

An insulin pump allows the replacement of slow-acting insulin for basal needs with a continuous infusion of rapid-acting insulin.

The insulin pump delivers a single type of rapid-acting insulin in two ways:[1]

Bolus shape[edit]

An insulin pump user can influence the profile of the rapid-acting insulin by shaping the bolus. Users can experiment with bolus shapes to determine what is best for any given food, which means that they can improve control of blood sugar by adapting the bolus shape to their needs.

A standard bolus is an infusion of insulin pumped completely at the onset of the bolus. It's the most similar to an injection. By pumping with a "spike" shape, the expected action is the fastest possible bolus for that type of insulin. The standard bolus is most appropriate when eating high carb low protein low fat meals because it will return blood sugar to normal levels quickly.

An extended bolus is a slow infusion of insulin spread out over time. By pumping with a "square wave" shape, the bolus avoids a high initial dose of insulin that may enter the blood and cause low blood sugar before digestion can facilitate sugar entering the blood. The extended bolus also extends the action of insulin well beyond that of the insulin alone. The extended bolus is appropriate when covering high fat high protein meals such as steak, which will be raising blood sugar for many hours past the onset of the bolus. The extended bolus is also useful for those with slow digestion (such as with gastroparesis or Coeliac disease).

A combination bolus/multiwave bolus is the combination of a standard bolus spike with an extended bolus square wave. This shape provides a large dose of insulin up front, and then also extends the tail of the insulin action. The combination bolus is appropriate for high carb high fat meals such as pizza, pasta with heavy cream sauce, and chocolate cake.

A super bolus is a method of increasing the spike of the standard bolus. Since the action of the bolus insulin in the blood stream will extend for several hours, the basal insulin could be stopped or reduced during this time. This facilitates the "borrowing" of the basal insulin and including it into the bolus spike to deliver the same total insulin with faster action than can be achieved with spike and basal rate together. The super bolus is useful for certain foods (like sugary breakfast cereals) which cause a large post-prandial peak of blood sugar. It attacks the blood sugar peak with the fastest delivery of insulin that can be practically achieved by pumping.

Bolus timing[edit]

Since the pump user is responsible to manually start a bolus, this provides an opportunity for the user to pre-bolus to improve upon the insulin pump's capability to prevent post-prandial hyperglycemia. A pre-bolus is simply a bolus of insulin given before it is actually needed to cover carbohydrates eaten.

There are two situations where a pre-bolus is helpful:

  1. A pre-bolus of insulin will mitigate a spike in blood sugar that results from eating high glycemic foods. Infused insulin analogs such as NovoLog and Apidra typically begin to impact blood sugar levels 15 or 20 minutes after infusion. As a result, easily digested sugars often hit the bloodstream much faster than infused insulin intended to cover them, and the blood sugar level spikes upward as a result. If the bolus were infused 20 minutes before eating, then the pre-bolused insulin would hit the bloodstream simultaneously with the digested sugars to control the magnitude of the spike.
  2. A pre-bolus of insulin can combine a meal bolus and a correction bolus when the blood sugar is above the target range before a meal. The timing of the bolus is a controllable variable to bring down the blood sugar level before eating again causes it to increase.

Similarly, a low blood sugar level or a low glycemic food might be best treated with a bolus after a meal is begun. The blood sugar level, the type of food eaten, and a person's individual response to food and insulin have an impact on the ideal time to bolus with the pump.

Basal rate patterns[edit]

The pattern for delivering basal insulin throughout the day can also be customized with a pattern to suit the pump user.

Basal rate determination[edit]

Basal insulin requirements will vary between individuals and periods of the day. The basal rate for a particular time period is determined by fasting while periodically evaluating the blood sugar level. Neither food nor bolus insulin must be taken for 4 hours before or during the evaluation period. If the blood sugar level changes dramatically during evaluation, then the basal rate can be adjusted to increase or decrease insulin delivery to keep the blood sugar level approximately steady.

For instance, to determine an individual's morning basal requirement, they must skip breakfast. On waking, they would test their blood glucose level periodically until lunch. Changes in blood glucose level are compensated with adjustments in the morning basal rate. The process is repeated over several days, varying the fasting period, until a 24-hour basal profile has been built up which keeps fasting blood sugar levels relatively steady. Once the basal rate is matched to the fasting basal insulin need, the pump user will then gain the flexibility to skip or postpone meals such as sleeping late on the weekends or working overtime on a weekday.

Many factors can change insulin requirements and require an adjustment to the basal rate:

A pump user should be educated by their diabetes care professional about basal rate determination before beginning pump therapy.

Temporary basal rates[edit]

Since the basal insulin is provided as a rapid-acting insulin, the basal insulin can be immediately increased or decreased as needed with a temporary basal rate. Examples when this is helpful include:

Advantages of pumping insulin[edit]

Disadvantages of pumping insulin[edit]

History of insulin pumps[edit]

In 1963 Dr. Arnold Kadish designed the first insulin pump to be worn as a backpack.[6] A more wearable version was later devised by Dean Kamen in 1976. Kamen formed a company called "AutoSyringe" to market the product, which he sold to Baxter Health Care in 1981.[7]

The insulin pump was first endorsed in the United Kingdom in 2003, by the National Institute for Clinical Excellence.

Acceptability[edit]

Use of insulin pumps is increasing throughout the world because of:

Recent developments[edit]

An early, large model of insulin pump, 78 x 12 x 22 cm.

New insulin pumps are becoming "smart" as new features are added to their design. These simplify the tasks involved in delivering an insulin bolus.

Future developments[edit]

Hypoglycemia and new developments[edit]

An important step forward is the MySentry system for an automated alert in case of nocturnal hypoglycemia, the development of algorithms for suspension of pump action in case of sensor detected imminent hypoglycemia, and the availability of stable glucagon solutions which will enable automated glucagon delivery from a second sensor activated pump.

Security[edit]

In August 2011, an IBM researcher, Jay Radcliffe, demonstrated a security flaw in insulin pumps. Radcliffe was able to hack the wireless interface used to control the pump remotely.[16] Pump manufacturer Medtronic later said security research by McAfee uncovered a flaw in its pumps that could be exploited.[17]

Choosing a pump[edit]

When the time comes to select an insulin pump, there are numerous options. The "perfect" pump varies by person. Factors such as weight, color, cost, canula insertion angles, special features, and easy usage play a vital role in the selection process. Patient factors relevant to infusion set selection include patient’s age, immune system function, body characteristics, activities, personal preferences, and history of diabetic ketoacidosis.[18] 

Popular pumps include the Asante Snap, Tandem t:slim, Animas One Touch Ping, Medtronic MiniMed, and OmniPod.[19] The process of selecting a pump usually involves the patient meeting with representatives from companies they are interested in. It is recommended for patients to do as much research as possible. All pumps have the same goal, and each takes a different route. On-line tools have been developed to assist with pump choice.[20]

Bibliography[edit]

References[edit]

  1. ^ http://www.diabetes.co.uk/insulin/Insulin-pumps.html Insulin pumps
  2. ^ Kesavadev J, Kumar A, Ahammed S, Jothydev S (2008). "Experiences with Insulin Pump in 52 Patients with Type 2 Diabetes in India". DiabetesPro. American Diabetes Association. 2021-PO. 
  3. ^ Conget Donlo I, Serrano Contreras D, Rodríguez Barrios JM, Levy Mizrahi I, Castell Abat C, Roze S (2006). "[Cost-utility analysis of insulin pumps compared to multiple daily doses of insulin in patients with type 1 diabetes mellitus in Spain]". Rev. Esp. Salud Publica (in Spanish; Castilian) 80 (6): 679–95. PMID 17147307. 
  4. ^ Kesavadev J, Rasheed SA. "Dramatic Response of Painful Peripheral Neuropathy with Insulin Pump in Type 2 Diabetes". DiabetesPro. American Diabetes Association. 2097-PO. 
  5. ^ Kesavadev J, Balakrishnan S, Ahammed S, Jothydev S (August 2009). "Reduction of glycosylated hemoglobin following 6 months of continuous subcutaneous insulin infusion in an Indian population with type 2 diabetes" (PDF). Diabetes Technol. Ther. 11 (8): 517–21. doi:10.1089/dia.2008.0128. PMID 19698065. 
  6. ^ https://wiki.engr.illinois.edu/display/BIOE414/The+History+of+Insulin+Pumps
  7. ^ http://www.diabeteswellbeing.com/who-invented-the-insulin-pump.html
  8. ^ http://animascorp.co.uk/animas-vibe-and-cgm-system
  9. ^ http://www.newswire.ca/en/story/1293917/animas-vibe-tm-insulin-pump-with-latest-dexcom-cgm-technology-now-available-in-canada-1
  10. ^ http://www.myomnipod.com
  11. ^ a b http://www.tandemdiabetes.com
  12. ^ http://www.diabetesmine.com/2013/03/oh-snap-asante-insulin-pump-isnt-a-pearl-anymore.html
  13. ^ [1], Humalog prescribing information.
  14. ^ [2], Linjeta duration of action .
  15. ^ [3], Novo pipeline .
  16. ^ Insulin Pumps Vulnerable to Hacking
  17. ^ "Exclusive: Medtronic probes insulin pump risks". Reuters. 25 October 2011. 
  18. ^ http://www.diabeteseducator.org/export/sites/aade/_resources/pdf/research/12-30-11-AADE_Insulin_WhitePaper_Print.pdf
  19. ^ http://www.diabetesnet.com/diabetes-technology/insulin-pumps/current-pumps/pump-comparison
  20. ^ http://insulinpump.com/

External links[edit]