Unexpected High Blood Sugar ?

15 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. Cannula 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 cannulas (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 looks fine, but will not absorb well. Some people are more likely to overlook a site problem if using a 90 degree (straight in) cannula as the infusion site can't be seen as well as it can be 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. Otherwise, you might put yourself at risk for high blood sugars, sore lumps or potential DKA. Checking and changing infusion sites regularly should be done regardless. See other reasons for this below.
  3. Large total daily doses of 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. For those of you not yet on a pump, you might be surprised (and relieved) to learn that there are various confirmatory steps in place to prevent accident delivery of insulin.
  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.
  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 usually equal to about a unit of insulin for many of the infusion sets (be sure to check with the company). 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. Small champagne bubbles in the reservoir are usually not an issue and do 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 intimate moments, and could result in DKA in a few hours (especially if going to be bed without reconnecting and sleeping through the night.)
  8. Ineffective connection of tubing to the hub or connector on the skin: No matter the infusion set, always gently tug the set when attached to the skin to be sure it is in.
  9. Infusion set ripped out:Most people would feel this. But... sometimes cannulas rip out during the night. This emphasizes the importance of testing glucose readings first thing in the morning to reduce the risk of DKA. For those whose sets don't adhere well, a clear soft protective covering like Tegaderm can be placed over the infusion sites. Others may use a special adhesive product on the skin prior to inserting a cannula. 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.
  10. 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.

  11. 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 some people on pumps eating high fat meals like pizza and Chinese food.
  12. 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.
  13. Accidental change or zeroing of basal rate:Sometimes people accidentally program their basal rate downwards when meaning to do a temporary basal. Keep a copy of your basal rates written on a calendar or journal just in case.
  14. 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
  15. Insulin pump failure: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) if your pump fails.

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.