Unexpected High Blood Sugar ?

17 unique causes of highs on insulin pump

There are many sneaky causes of high blood sugar, as people with diabetes well know. Understanding the reasons can reduce the frustration and help prevent future episodes. Everyone with diabetes could benefit from reading this list of causes for high blood sugar. Click here for this general list. For insulin pumpers, what follows are unique reasons for sudden hyperglycemia (high readings) when on an insulin pump.

Stay safe.Read the disclaimer.See your doctor for all medical advice.This site isn't medical advice.

17 Causes of High Blood Sugar Related to Insulin Pumps

  1. Review all the reasons for diabetes-specific causes for high blood sugar if you haven't already. Although not pump specific, they are often the primary reason for sudden hyperglycemia in the pump clients I see. Definitely review the insulin pump causes below, but not at the expense of forgetting about all the "non pump" causes.
  2. Canula left in too long: This is by far the most common insulin-pump-related cause for hyperglycemia. Many people exceed the recommended 2-3 day wear for canulas (the part of the infusion set that is under your skin). It doesn't always pose a problem, however the more insulin you take the more of a problem it is likely to cause. Tissue that is irritated does not readily absorb insulin as well as it should. Sometimes the site looks pink, puffy and sometimes it doesn't. You are more likely to overlook a site problem if you are using a 90 degree (straight in) cannula as you can't see the infusion site as well as you can with a 30 degree infusion set. This doesn't mean you need to switch sets, only that you need to remember to change them rather than rely on looking at them to see how they are doing. Although, checking infusion site regularly should be done regardless. See other reasons for this below.
  3. More than usual insulin: If you give bigger boluses or more insulin overall, like at Christmas due to the sweets etc, then your site may not last as long as it usually does for the same reasons listed in the point above. If changing the set more often due to eating more carbs during Christmas, Halloween or holidays is a concern due to cost, talk with your health care provider about giving bigger boluses by syringe or insulin pen and using the pump just for basal insulin during those periods in your life. The site will last longer.
  4. Forgetting to confirm a bolus: If you ask for a bolus by hitting a few buttons and not looking at the pump, the pump may beep or vibrate back to confirm the units you've asked for (eg. if you are not using the built in calculator). Usually, you have to hit a button after this to confirm the bolus. If you don't, the pump can cancel the bolus (although usually you'll get a few beeps to notify you that it did not give the bolus). If you have an unexplained high, check back in your bolus history to see if the bolus was actually delivered.
  5. Site irritation:This could be as simple as inflammation from your waistband on pants or as bad as a site infection. Site irritation, lumps or infections all negatively affect insulin absorption and can cause high blood sugar. And of course, infections require medical attention with antibiotics as the site gets extremely swollen and tender as it progresses. I compare an advanced infection to what I think a tarantula bite would look like. I'm guessing but you get the picture - ugly and ouwee.
  6. Large air bubbles in the tubing or reservoir: Air into fat tissue is not a big issue for safety but can be for high blood sugars. An air bubble of about an inch in length inside tubing is equal to about a unit of insulin for many of the infusion sets. Depending on how sensitive you are to insulin, that could increase blood glucose readings. Of course, most air bubbles come from the insulin reservoir in the pump. Read here for 8 tips on eliminating air bubbles from insulin pump reservoirs. Small champagne bubbles in the reservoir are usually not an issue and does not typically result in high blood sugar. Bigger bubbles often pose a bigger problem when the reservoir is nearer to being empty.
  7. Forgetting to re-connect pump: This could be after shower or sex! Yippee! Umm....not for forgetting to re-connect but for...ahem. I'll stop now. But really, forgetting to reconnect after the fun is a common problem and since the fun often happens at night, potentially you could wake in in DKA. Bad stuff. So maybe set a timer. No, silly. Not to time your fun, but to remind you to re-connect the pump. Timing the fun might be ...errr...disappointing?? (hope not )
  8. "Suck back" after disconnecting then reconnecting.Although they say that newer pumps don't "suck back" air into the tubing when disconnected, I personally have found that they do. For some folks, they see no issues with disconnecting, showering, reconnecting. However, some people do get a high glucose reading afterwards on an irregular basis. Why not try doing an external prime, where you are not connected to the pump, until you see the insulin come out the end of the set before reconnecting (stop the prime before reconnecting). If you do this on 3-4 occasions you may notice that sometimes the insulin comes out immediately, but other times, it may take a fraction of a unit or more before you see insulin come out due to "air suck back". The most I've seen my old Disetronic H-Tron suck back air was 5 units. Yes, egad! My Medtronic Paradigm, which I love, I've seen suck back almost a full unit. But not with every disconnect. Sometimes there is no suck back.
  9. Tubing re-used too many times:I don't know the reason off hand, but it seems that tubing that is used over and over and over (even though the cannula is changed) often results in hyperglycemia. This may or may not be the case for you.
  10. Ineffective connection of tubing to the hub or connector on the skin: Make sure you hear a "click" if it's a 30 degree set. No matter the infusion set, always gently tug the set when attached to the skin to be sure it is in. The first time I used a new 90 degree set, I didn't fully make the connection. Yes, I suffered for that mistake. But not for long since I test my sugars within 1-2 hours of all set changes. Also, myself and other clients have had the end of the tubing pull out from the hub at the end of the pump and also at the hub/connection to the canula on the skin. (basically disconnects like someone took scissors to it - how lovely).
  11. Infusion set ripped out:I know, you're thinking, "Hey! I'd feel that!" Well, usually we do. But... sometimes canulas rip out during the night without you knowing. Of course, if you wake up with a sky-high blood sugar reading, check this. Also, sometimes I find my tubing is not connected when I go to use the restroom - especially after horse riding. If your infusion site is subject to a lot of movement, check often or consider using a different site those days. For example, I try to use my arm, not my abdomen, when I ride now. Also consider using a safety loop of tape to reduce the risk of this happening. Where the tubing is attached to your skin, loop the tubing and place a strip of soft tape over the loop attaching it to your skin. Then if the tubing yanks, the tape and the loop are the first things to take the force and come undone but the canula is still in the skin. See near end of this list for sweating issues causing the canula to come out.
  12. Not priming tubing when re-using it:Many sets allow for tubings to be re-used once. However, even though there is insulin in the tubing, still go through the entire normal set-up as if the tubing were new. There could be suck back of air on both ends of the tubing. More likely, what could happen is that without doing that priming, the plunger inside the pump does not fully seat itself at the base of the insulin reservoir. This means the internal plunger could be pushing forward with no alarms etc but also without making contact with the base of the reservoir for quite a few units. So no insulin in the tubing would move.
  13. Need for different type of bolusing:Some meals just don't do well with the normal or standard bolus. Talk with your educator to see if you could benefit from using dual wave/combination boluses where some of your insulin is given right away and the rest over a period of time that you select. This works well for high fat meals like pizza and Chinese food.
  14. Previous decreased temporary basal or disconnect:Sometimes pumpers temporarily stop their basal, disconnect for a sport or use a temporary decreased basal. This is often done to reduce the risk of hypoglycemia but is sometimes one of the causes of high blood sugar later on. Remember, rapid insulin works in 15 minutes for some but has a duration of up to 4 hours in many people (although the later part of the action time is not strong). So any change you make now, could potentially affect you now and much later on. Oh, and sometimes people set a very long decreased temporary basal and simply forget.
  15. Accidental change or zeroing of basal rate:Sometimes people accidentally program their basal rate downwards when meaning to do a temporary basal. Older pumps sometimes zeroed the basal rates when hit with static electricity. Keep a copy of your basal rates written on a calendar or journal just in case.
  16. Sweating off, tunneling, O-ring leaks, hub leaks...All very unique pump problems. Please see this page of diabetes.net for descriptions. http://www.diabetesnet.com/diabetes_technology/insulinpumps_problems1.php
  17. Insulin pump failure:Rare. Really, really rare. But still possible. If happens, immediately call the 1-800# on back of pump for a replacement. To prevent or treat high blood sugar, be sure to have an emergency kit at home that has a prescription for your dose of backup basal insulin (eg. NPH, N, Glargine, Lantus etc) with either syringes or insulin pen. Be sure to have guidelines from your educator on how to manage high blood sugars and prevent DKA (diabetic ketoacidosis).

Do not hesitate to seek urgent medical care if you are on an insulin pump and experience high blood sugars with ketones that you cannot manage or reduce yourself.


Other diabetes-specific reasons for hyperglycemia, whether on insulin pump or not.