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Insulin Pumps

What are they, how do they work, and what are the advantages?

The number of pumpers in the diabetes world has been growing rapidly! Although this is partially due to the more recent advances in pump therapy, it can also be attributed to passionate pumpers (like myself) sharing their experiences. Deciding to switch from multiple daily injections (MDI) to pump therapy is a pivotal point in a diabetic’s life. For those of you who have already chosen this, I congratulate you. You have given yourself a wonderful opportunity for not only improved control, but for an improved quality of life. For those of you who have decided against pumping or are “on the fence”, let discuss!

What exactly is a pump and how does it work?

A pump is a small mechanical device (much smaller than a cell phone) which delivers insulin through a catheter under the skin called an infusion site. The infusion site is placed with a small needle and is changed ~every 3 days by the user. The needle is removed leaving the flexible plastic catheter under the skin (~ the size of a couple of hair strands placed together), which is then taped down and attached to a tube which connects to the pump’s reservoir (where the insulin is held). The pump delivers insulin in 2 ways; basal and bolus.

Basal insulin is a small spurt of rapid acting insulin (Humalog, Novolog, Amdelog, Fiasp or Apidra) delivered every few minutes over a 24hr period. This feature eliminates the need for long-acting insulin (Lantus, Levemir, Basaglar, Tresiba, Toujeo) and can be tailored to each patient’s needs.

For example; Sally and Dan’s BGs have a very similar pattern. Both wake up with high BGs in the morning due to “dawn phenomenon” (increase in BGs ~3am when liver kicks out excess glucose), and both work very physically demanding jobs. Because of this they tend to have low BGs around 4pm, just before they leave work. Sally uses an insulin pump, and Dan uses MDI.

Dan: After consulting with his clinician Dan decided to increase his long-acting insulin from 40 units to 42 units to combat his “dawn phenomenon”. He now wakes up with perfect BGs, however his lows during work have gotten much worse! He could eat to prevent these lows, but he has been trying to lose weight and hates eating when he isn’t hungry! After speaking with his clinician again, he decides to decrease his long-acting insulin down to 38 units. He is so sick of the lows! He no longer goes low at work, but now his morning BGs are even higher than before giving him a poor start to the day.

Sally: After consulting with her clinician Sally changed her pump settings (basal rate) to give her more insulin during the early morning hours to combat her “dawn phenomenon” and less insulin during her work hours to prevent her hypoglycemia. She now has steady, at goal BGs throughout the entire day which makes her feel great!

Not only does Sally avoid her highs and lows using a tailored basal rate, but she has a much more flexible eating schedule. She does not have to deal with the unpredictability of long acting insulin peaks and therefore does not go low if her meals are skipped or delayed. As you can see, this is a much better option!

Now let’s talk about bolus.

Boluses are the larger amounts of insulin given before meals to cover carbohydrates or to correct high BGs. Many of you using MDI do this with your rapid-acting insulin already, so what are the benefits of blousing through a pump?

All pumps come equipped with a bolus calculator which uses personalized settings to calculate specific insulin requirements based on carbs being ingested and current BG reading. Many people who use carb counting to dose insulin use what’s called a “carb factor”, or insulin to carb ratio (ex: 1 unit for 15 grams of carbs), and a “correction factor”, or insulin to BG ratio (ex: 1 unit for every 50mg/dl >100mg/dl). The bolus calculator not only does these calculations for you, but it can deliver the insulin in small increments (as little as 0.10 units) making the doses much more specific. Most MDI boluses must be given in 0.5-1.0 unit increments.

My favorite feature of the bolus calculator is the insulin-on-board (IOB) feature. This feature is used to prevent “insulin stacking” by calculating how much insulin is still active in the body and subtracting that from the current calculated insulin dose (preventing hypoglycemia).

Other pump positives include:

-The ability to give multiple boluses if you decide to eat more than you originally planned

-Elimination of individual insulin injections

-More accurate boluses -

Improved HbA1c’s (with less lows and BG variability)

-Ease of insulin calculations!

-More flexibility of what you eat and when (no lows when meals are skipped or delayed due to tailored basal insulin flow)

- Exercise without consumption of large amounts of carbohydrates

There are way too many beneficial features of insulin pumps to be discussed in one post! They can even be used in conjunction with a CGM for additional improved control.

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