When High Blood Sugar Occurs in Patients Using Insulin Pumps at Home: A Comprehensive Guide

Managing high blood sugar is a critical concern for individuals using insulin pumps at home. If blood glucose levels remain elevated for an extended period, it can lead to serious complications such as diabetic ketoacidosis (DKA), which can be life-threatening if not addressed promptly. Understanding how to identify and manage high blood sugar effectively is essential for anyone relying on insulin pump therapy.

Initial Steps to Take When Blood Sugar Rises

When a person on insulin pump therapy experiences high blood sugar, the first step is to drink plenty of water to stay hydrated. Next, it's important to identify the underlying cause—such as pump malfunction, infusion site issues, or insulin absorption problems. Once the cause is addressed, further action can be taken to bring blood sugar levels back into a safe range.

Calculating the Correct Insulin Dose

Begin by measuring the current blood glucose level and use the insulin sensitivity factor (ISF) to determine the appropriate correction dose. The ISF indicates how much one unit of insulin will lower blood sugar. This value varies from person to person and depends on the total daily insulin dose.

For example, consider a patient named Xiao Wang who uses a biologically synthesized human insulin formulation. His total daily insulin dose includes a basal rate of 20 units plus boluses of 8 units for breakfast, 7 for lunch, and 7 for dinner, totaling 42 units per day. Since he uses regular (short-acting) insulin, his ISF would be calculated as follows:

ISF = 83 ÷ Total Daily Insulin Dose = 83 ÷ 42 ≈ 2

This means that each unit of insulin lowers his blood sugar by approximately 2 mmol/L.

Applying the ISF in Real-Life Scenarios

If Xiao Wang's current blood sugar is 18 mmol/L and he wants to bring it down to around 8 mmol/L, he would calculate the required insulin dose as follows:

(Current Blood Sugar – Target Blood Sugar) ÷ ISF = (18 – 8) ÷ 2 = 5 units

After administering this correction bolus, it's important to wait at least one hour before rechecking blood sugar levels. Keep in mind that only about 25% of the insulin will have taken effect after one hour, so a significant drop shouldn't be expected immediately.

Managing Residual Insulin and Repeating Doses

When considering a second correction dose, it's crucial to account for the remaining insulin still active in the body. In Xiao Wang's case, after one hour, about 1.25 units of the initial 5-unit dose will have taken effect, lowering blood sugar by approximately 2.5 mmol/L. There will still be about 3.75 units of active insulin remaining in his system.

If blood sugar remains high after the first dose, a second correction can be given, but the residual insulin must be subtracted to avoid hypoglycemia. Always monitor closely and adjust doses carefully.

How to Calculate Your Insulin Sensitivity Factor

The formula for calculating ISF depends on the type of insulin used:

Short-acting insulin: ISF = 83 ÷ Total Daily Insulin Dose
Fast-acting insulin: ISF = 100 ÷ Total Daily Insulin Dose

The total daily insulin dose includes both basal and bolus insulin delivered over a 24-hour period.

When to Replace Equipment and Reassess

If blood sugar remains high despite correction doses, consider replacing the infusion set, reservoir, and insulin vial. Choose a new infusion site and restart insulin delivery. In most cases, this step resolves the issue.

Escalating Care When Blood Sugar Doesn't Drop

If blood sugar does not decrease after one hour, switch to an insulin pen or disposable syringe for manual insulin delivery. If blood sugar still doesn't drop after another hour, contact a healthcare provider immediately.

Recognizing and Managing Diabetic Ketoacidosis (DKA)

If a patient's blood sugar exceeds 16.7 mmol/L and they experience symptoms like fatigue, nausea, vomiting, or a fruity odor on their breath, ketoacidosis may be developing. In such cases, test for ketones in the blood or urine right away.

If symptoms are mild, hospital treatment with intravenous fluids is recommended. If immediate medical care is not possible, follow these emergency steps:

Drink plenty of water to combat dehydration.
Remove the pump and infusion set if a blockage or malfunction is suspected.
Administer short- or ultra-short-acting insulin via syringe or pen, increasing the dose by 50–200% or using 20% of the total daily insulin dose. Repeat every 2–3 hours.
Monitor blood sugar every 1–2 hours, aiming for a 10–15% decrease per hour.
Check urine ketones every 2 hours until they disappear.
Once ketones are negative and blood sugar is below 11.1 mmol/L, consume 15–20g of carbohydrates and restart the insulin pump.
Account for residual insulin activity when calculating any additional correction doses.

When to Seek Immediate Medical Help

If symptoms worsen—such as severe weakness, persistent vomiting, or inability to drink—seek emergency medical attention immediately. Intravenous fluids and insulin therapy are often required to treat severe ketoacidosis safely.

Being prepared with the knowledge and tools to manage high blood sugar at home can make a significant difference in outcomes for insulin pump users. Always keep emergency supplies on hand and maintain regular communication with your healthcare provider.