Infusion Set Failure

A Cause for Unexplained High Glucoses (UHGs) on a Pump

Today’s infusion sets offer many improvements and options, yet reports and blogs suggest issues with infusion sets are widespread. Only a handful of studies have directly looked at this problem.1 Infusion set leaks and failures create random unexplained high glucose values (UHGs). They also make up most phone calls to manufacturers and end up being a common reason that people stop wearing a pump. The Weak Spots graphic shows all the ways you can lose insulin, but nearly all UHGs arise from the infusion set, NOT from pump failure or having a “bad infusion site.” So set detachments and leaks along a Teflon cannula or steel needle are the most common sources for UHGs. Go Here if you are unfamiliar with an abbreviation or term.

Weak Spots in Insulin Delivery

Infusion set failure represents the great white whale on your quest for good glucose readings. Lurking just below the surface, it bumps your glucose high and sets you up for failure. Infusion site failures are a common source for UHGs compared to “bad infusion sites” or “bad insulin”, two extraneous causes that often get the blame.  Don’t be Ahab – catch the great white whale!

Four research studies have looked at initial failure rates when Teflon sets are inserted with an auto-inserter. Initial failures ranged from 3.2%2, to 8.9%2, to 10%, to 15%3. Among 1,142 German pump wearers, 72% of those who used an auto-inserter reported that it failed to work ~10% of the time.4 Set failures average 0.3-2.2 times/month for 2-3 day set use. In a review of a head-to-head comparison of two current infusion sets, 19% of both infusion sets required unexplained catheter replacements after insertion. Dr. Eric Renard, the main author, stated, “Fixing this weak aspect of CSII [insulin pump therapy] becomes crucial while moving toward closed-loop insulin delivery.”

If you’re on a pump, you probably use the infusion set brand that you started with, one recommended by your doctor or CDE, or one sent to you by the pump manufacturer. You probably haven’t given it a second thought since starting. The infusion set often doesn’t come to mind as a significant source for glucose control problems. Infusion set problems, unfortunately, cause far more hyperglycemia for those whose glucose levels are highest.

Having more than one infusion set failure a month raises the A1c.

Set failures can be hard to recognize. Pump wearers often change their infusion set and site any time they encounter unexplained high glucose readings. This is often done grudgingly without fully realizing that this intermittent problem is coming from their infusion set.

A Graph of Glucose Levels Before and After Infusion Set Changes

This graph of unpublished Glucose Level data from the Actual Pump Practices study shows average glucose levels in 6-hour intervals beginning one day before a person changes their infusion set up to 6 days afterward. There was an average of 20 infusion set changes per person among these 396 pump wearers.

Note the very large 30 mg/dL fall in average glucose levels 12 hours after infusion sets are changed. This drop occurs as insulin delivery again becomes fully reestablished. Note also that glucose levels immediately begin to rise as infusion set problems gradually reappear.

An alternate explanation could come from decay in insulin activity over time within a pump reservoir, but John’s experience with thousands of pumpers does not agree with this theory. He has seen many pumpers who have UHGs suddenly have this problem disappear once they start anchoring their infusion sets. He and many of his patients wear infusion sets longer than 3 days with no loss of control.

To evaluate your current infusion set, answer these questions:

  • Do you have to change your infusion set before 3 days of wear?
  • Does your glucose often rise on day 2 or 3 of set wear?
  • Do you often have UHGs (unexplained high glucoses)?
  • Do some highs only correct after you change your infusion set?
  • Do correction boluses sometimes not work as they should?
  • Do unexpected highs appear right after changing your infusion set?
  • Do sites sometimes not work, or have you been told you have “bad sites, scarring or poor absorption”?

If you answer “yes” to 1 or more of these questions, you will likely reduce the glucose waves you face by re-evaluating your infusion set technique. You can also look at your CGM graphs for any unusual pattern of UHGs where your glucose goes high and doesn’t come down until the set is changed.

Assume your infusion set has failed any time that you experience 2 unexplained highs in a row that don’t respond to correction boluses or remain high for over 5 hours on your CGM. Give an injection immediately to bring the glucose down. The dose will often be higher than expected due to the prior loss of basal insulin. Then change your site, infusion set, and reservoir.

Inspect your site and line anchoring. Teflon sets require a tape “anchor” at all times because any tugs on the line transfer directly to the Teflon cannula and increase the likelihood of a leak. Review site preparation and set insertion technique, and always remember to anchor your line.

Teflon or Steel?

Teflon cannula infusion sets, while purportedly more comfortable than steel sets, are not more comfortable but are often to blame for infusion set failure. Failures with Teflon sets can occur at any time, are occasionally seen right after insertion, but are most common on day 2 or 3. Quick-sets are especially prone to failure due to the pinch, twist, and pull motion used to disconnect and reconnect the line directly above the Teflon cannula when bathing or any other time the pump is disconnected.

3.3 Infusion Set Options
Steel Polymer
  • No Kinking
  • Straight
  • Lower profile for children, sports, or carrying a child
  • Disconnects away from needle – anchoring only needs to be done once at the insertion
  • Easier to insert and train
  • No tugs on the needle
  • Few silent occlusions
  • Small 28-30 gauge needle
  • Better biocompatibility and less back pressure
  • More Selections
  • Straight or slanted
  • Higher profile
  • Disconnects at cannula – anchoring of line advised after each disconnect
  • Manual or automatic insertion
  • Tugs directly on cannula if the line is not anchored
  • Less needle phobia with auto-inserter
  • Larger 25 gauge Teflon (27-ga introducer needle) or 28 gauge with FlowSmart (30-ga introducer needle)

Set failures typically do not trigger an occlusion alarm because they don’t block the tubing but result from a slow leak of insulin along the Teflon cannula to the skin surface or a faster leak when the set completely detaches. In a recent study of pigs who had 30° or 90° Teflon infusion sets changed every two days over two weeks, the 30° slanted set reduced inflammation significantly (9.1 versus 14.3 square millimeter, p < 0.001) and the thickness of inflammation (0.7 versus 1.2 mm, p < 0.005) at the infusion site compared to 90° sets, and they also had a wider distribution of insulin for better absorption.5 This may minimize site issues.

While testing your pump settings to optimize them, we highly encourage you to use a steel set like the Medtronic Sure-T, Tandem TruSteel, or Contact Detach for Luer lock pumps. Their short 6 mm fine gauge needle under the skin is as comfortable as Teflon, and more importantly, dependable, eliminating the particularly infuriating variable of set failure. To switch to steel, you can usually contact your distributor. On occasion, a new prescription is needed.

Many people safely ignore the “2 days of use” recommended by manufacturers for steel sets, even though there is no documentation for this.  Among 534 pump wearers in the U.S., Teflon sets were used for an average of 3.4 days and steel sets for 3.7 days.6

Infusion Set Tips:

  • Use an infusion set with a high success rate: 6 mm steel (or a shorter one, if available). The tubing connector for steel sets is about 4” away from the insertion. The remote detachment allows an IV3000 or Tegaderm adhesive to be placed on top of the site with most of the adhesive placed over the tubing. This is done only one time after inserting a new set.
  • Always anchor the infusion line to eliminate any movement of the needle or cannula from pump drops or tugs. For 30° or 90° Teflon sets, always place a short length of 1” Durapore or similar tape over the line about 3” away from the cannula. Replace the tape each time after bathing or detachment.

Goal: Allow no more than one infusion set failure a year.

For more information about infusion sets, see our Infusion Set Comparison page or read Chapter 15 of Pumping Insulin.

Next, check your pump settings.


1 Heinemann L, Fleming GA, Petrie JR, Holl RW, Bergenstal RM, Peters AL. Diabetes Care. 2015; 38: 716-722.

2 Renard E, Guerci B, Leguerrier AM, Boizel R. Analysis of “Randomized Cross-Over Study Comparing Two Infusion Sets for CSII in Daily Life” Diabetes Technol Ther. 2010;12:769-773.

3 Patel PJ, Benasi K, Ferrari G, et al. Diabetes Technol Ther. 2014;16:15-19.

4 Heinemann L, Weber D, Kaltheuner M, Scheper N, Faber-Heinemann G, Reichert D. Abstract #994-P. American Diabetes Association 73rd Scientific Sessions, Chicago, IL, 2013.

5 https://drc.bmj.com/content/7/1/e000881

6 Walsh J, Roberts R, Weber D, Faber-Heinemann G, Heinemann L. J Diabetes Sci Technol. 2015, Vol. 9(5) 1103–1110.

14 thoughts on “Infusion Set Failure”

  1. After 26 years of being on an insulin pump the last year or two has seen a dramatic rise. I was doing so well and take excellent care of myself but this is unbelievable. I have an almost 100% initial failure rate; yup, EVERY…. SINGLE….. ONE is failing. After changing sets I often get skyrocketing sugars. When I take it out it often tends to bleed. Just because I change it doesn’t mean it gets fixed. Often I need to put it 2, or even 3 to get “good luck”.

    It doesn’t matter where I put it in. Tried back of arms and legs too where I might be giving shots as well to put them in it always fails, high sugars after every one of them. The last month and a half or two pretty much every single insertion fails. Had a minimed pump back in 1995 which went to Medtronic. Am due for a new one and am considering switching. Although it worked so well for so long any pumps out there with better luck and more reliable sets?

    Reply
    • Hi Attilio,
      Sorry to hear about the set failures. Please let us know more about what happens:
      1. Which infusion set are you using?
      2. Let us know about rotation. Do you normally rotate sites over the whole abdomen, above and below your beltline, on the flanks, upper buttocks, etc.?
      3. How high and how soon do your BGs rise after putting in a new set?
      4. After inserting a “good” set, are your BGs then relatively normal?
      5. Are there any other signs of a failed set such as a damp adhesive, or liquid or the odor of insulin on the skin?

      Thanks,
      John

      Reply
  2. Would you recommend at pump change an increase in basal or a upfront bolus to cover the time it takes for the pump to re establish full control?
    I sometimes take 2 units since I find the pump needs two hours to re-establish control were i miss 2 hrs of basal, the bolus also works equal to the amount of basal issued.

    Reply
    • A 2 unit bolus would be appropriate if you consistently have your glucose rise when you change infusion sets. A basal adjustment would take longer to have an effect. You might consider a smaller bolus if the rise in glucose is not consistent.
      If you are using a Teflon infusion set, they are prone to silent occlusions. Becton Dickinson researchers looked at this carefully. A silent occlusion occurs shortly after insertion when tissues around the cannula compress it and reduce the flow of insulin. The glucose then rises but the pump does not alarm, hence the “silent” in front of occlusion.
      FYI, steel sets don’t do this, are easier to insert, and are generally worn longer than Teflon sets. Might be worth a try!

      Reply
  3. A Pumper’s Question:
    “I have a Tandem pump and use the Auto Soft 90. About one in eight or ten times there is a failure resulting in very high glucose and I have to change the infusion set. The main cause is the adhesive backing pulls up when I disconnect from the insertion device. I have told Tandem about this and evidently, they don’t care. I never had this problem with AccuChek infusion sets.
    Can I change to a more reliable infusion set made by another company?”
    Response:
    Infusion sets have always been the weak link for insulin pumps. As you’ve noticed, some auto-inserters don’t always fully detach from the set when the spring retracts. This leads to a kink in the cannula or insulin leaking back to the skin along the cannula. Unfortunately, all pumps have a proprietary connection to the pump body, so the Auto Soft is the only similar set that I am aware of for the Tandem.
    A quite reliable alternative is the TruSteel 6 mm set. It’s easy to insert, much less likely to fail, has a flat profile on the skin, and is usually worn longer than Teflon sets. I cover the insertion site and part of the infusion line with an IV3000 or Tegaderm adhesive, after removing the adhesive at the connector base about 4 inches away. This over-bandage keeps the set securely connected to the skin for the duration of wear. You can then easily detach for showers, etc., and with the connector base unattached to the skin, it provides a longer infusion line. Your goal is to have no more than one infusion set failure a year. Might be worth a try!
    You learn a lot after 39 years on a pump! ;-)

    John Walsh, PA, CDTC

    Reply
  4. I use the Medtronic 630G and every single set change of Cannula & Reservoir gives me 6 to 8 hours of very High Glucose readings. I have to increase the Basel up to 5 units in increments of 30 minutes depending on the glucose readings from my Dexcom. My A1C has increased from 6.9 to 7.7. I have changed sites a bunch of times but to no avail. Maybe I might have “LIPODYSTROPHY”. Any suggestions?

    Reply
  5. Hi Fara,
    Lipodystrophy is a very uncommon reason for very high glucose readings after set changes. I assume your set change does not take a couple of hours and you are priming your infusion line and have insulin visible on the cannula tip?
    Was this happening when your A1c was 6.9%?
    Is there any other reason for the higher A1c, such as an increase in weight, decreased activity, or change in diet? If there is another reason, you may need to raise your basal or lower your CarbF (iSF).
    With the higher A1c, your basal rate high be too small and the time to change the set may send the glucose higher. Check in your pump history to verify that your basal rate makes up at least half of your total daily insulin dose. If not, consider raising your basal rate, which you may need to do anyway with the higher A1c.
    Another option is to change to a different type of infusion set to see if that corrects the problem.
    Good luck,
    John

    Reply
    • This is a weak answer. People who have used a pump and all of a sudden have unexpected high bg readings after a set change myst be common. Something has to be wrong… very wrong. 50 percent of the time my infusion sets don’t take… They used to but now don’t. Steel cannula 6mm or 8mm all the same. Unbelievable to say the least. Something has changed and not in a good way.

      Reply
      • I had had set failures before but not very often. The recency of your problem sounds very familiar. Not tried steel yet though.

        Reply
      • I agree with you Paul. I think the manufacturer’s sales have increased dramatically in recent months and in “tandem” with increased sales is a decrease in quality control. I’ve only been on Tandem for 7 months using TruSteel both 6 and 8 mm, and the number of infusion set failures I have experienced is totally unacceptable. It is our HEALTH at stake! And our pocketbook, those things are expensive! I am just about ready to quit this scene.

        Reply
        • In the care of hundreds of pumpers using the 6 mm TruSteel, BGs rising when the set changes DOES happen but is rare. With the TruSteel set, I encourage not using the second adhesive for the connector, but removing it and always placing a 3″ length of 1″ Durapore tape over the line a couple of inches away from the set. This reduces movement on the steel needle from kinking that sometimes occurs between inserting the infusion set and tacking down the connector adhesive. This ensures proper anchoring with no loop between the anchor and the set.
          I have not noticed a loss of quality in manufacturing these sets. Remember, if one set seems to cause problems, always try another set. This ends the problem if the set is the cause.
          In the Actual Pump Practices Study, the average glucose rose higher for each day of use. This suggests loss or leakage of insulin. Nearly all participants used Teflon sets. If the glucose is higher toward the end of set use, this may contribute to the glucose being higher after changing sets. Your liver reads insulin, not glucose levels, and will release more glucose as the glucose approaches 140 mg/dl. Good anchoring on the cannula might help.
          Per Paul’s “weak answer, ” an answer becomes much clearer when you clearly explain the problem and its circumstances.

          Reply
  6. I am so grateful to have found this article. About the past month, I have been ready to lose it, with multiple styles of teflon-cannula sets failing. Now I know to switch to steel! TYVM!

    Reply

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