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High blood sugar in insulin pump therapy

Insulin pumps use rapid-acting insulin. If the insulin supply is interrupted for any reason, blood sugar starts to quickly rise within a few hours. The cause must always be identified.

If during insulin pump therapy the glucose sensor reading is unexpectedly high, it should be verified with a fingertip blood glucose self-masurement. An unexpectedly high blood sugar refers to a value over 14 mmol/l that is not due to an underestimation of carbohydrates, a delay or omission of mealtime insulin, or insulin resistance caused by sick days.

The insulin used in pumps is rapid-acting, and there isn't the same kind of insulin reserve under the skin as there is when using long-acting basal insulin. When insulin delivery is interrupted, blood sugar can rise significantly within a couple of hours, and a lack of insulin leads to the accumulation of ketones. Diabetic ketoacidosis (DKA) can develop within a few hours.

In pump therapy, interruptions in insulin delivery can be due to pump malfunction, infusion set blockage, or problems related to the cannula site such as a bad site, cannula detachment, cannula bending, or poor insulin absorption due to tissue damage, for example.

If blood sugar rises above 14 mmol/l, identify and correct the cause.

Action Plan:

  • Inject rapid-acting insulin using a spare pen or insulin syringe from an insulin vial.

  • Check ketones with a ketone meter.

    • If ketones are above 1.5 mmol/l, take a larger than usual correction dose of insulin and drink plenty of water.

    • If ketones are above 3 mmol/l, contact the emergency department.

    • If you feel unwell or have symptoms of acid poisoning such as abdominal pain, nausea, or vomiting, go to the emergency department.

  • Check the pump and cannula operation:

    • Cannula and tubing

      • is it detached?

      • Is insulin leaking?

      • Is there air in the tubing or reservoir?

    • Insulin:

      • Has it been more than 3–4 days since the change?

      • Has it been exposed to heat or has it been frozen?

    • Cannula site:

      • Is there any hardening or swelling?

      • Is the cannula bent?

  • If no other cause is found, insert a new cannula at a new site.

  • Ensure the pump’s battery has power.

  • Measure blood sugar and ketones 1–2 hours after injecting the additional insulin.

Updated 4.11.2023