What to Do When Your Child's Blood Sugar Won't Come Down

You gave insulin. You waited. You checked again. The number is still 280, or 320, or it’s creeping higher. Now what?

Persistent high blood sugar — readings above your child’s target range that don’t respond to a correction dose within 2–3 hours — is one of the most stressful situations in day-to-day diabetes management. This guide walks through the reasons it happens and exactly what to do at each stage.

First: Don’t Panic, But Don’t Wait Either

A single high reading is data. A reading that stays high or climbs after a correction is a problem that needs troubleshooting. The difference between “concerning” and “emergency” usually comes down to two things: how high, and whether ketones are present.

Your first step any time blood sugar won’t come down: check for ketones.

Ketone Testing: Blood vs. Urine

Blood ketone meters (like the Precision Xtra or Nova Max) are significantly more accurate and faster to act on than urine strips. If your team has approved blood ketone testing, use it.

Urine ketone strips have a significant lag — they reflect ketones from 2–4 hours ago, not the current moment. A “moderate” urine result could already be “large” by blood testing.

The 5 Most Common Reasons Blood Sugar Won’t Come Down

1. The injection site isn’t absorbing insulin

This is the most common cause parents overlook. Subcutaneous insulin absorption varies significantly based on injection site, tissue condition, and temperature. A 2015 study in Diabetes, Obesity and Metabolism found up to 25–50% variability in insulin absorption between injection sites on the same person.

Lipohypertrophy — lumpy, hardened fatty tissue that forms at injection sites used repeatedly — absorbs insulin poorly and unpredictably. If your child has been using the same small area of abdomen for every injection, feel the area with your fingertips. If it feels lumpy or rubbery compared to surrounding tissue, that site is compromised.

What to do: Give the next correction dose at a completely fresh site — a different area of the abdomen, the outer thigh, or the back of the upper arm. Rotate sites systematically. This alone often resolves the problem.

2. The insulin pen or pump has a problem

For injection users:

• Is the insulin clear? Cloudy rapid-acting insulin (Humalog, NovoLog, Fiasp) has degraded and won’t work — replace the vial.
• Did insulin leak back out after the injection? Particularly in young children who move, a portion of the dose is sometimes lost.
• Was the pen primed before the dose? Air in the cartridge can mean less insulin is delivered than shown.
• Has the insulin been exposed to heat? Insulin left in a hot car, near a heating vent, or in direct sunlight degrades rapidly.

For pump users:

• Check the infusion site for kinking, redness, or swelling — a kinked cannula delivers zero insulin
• Check for air bubbles in the tubing
• When did you last change the infusion set? Sets older than 3 days absorb poorly
• Is there insulin in the reservoir?

3. Hidden carbohydrates or a meal that’s absorbing slowly

Some foods spike blood sugar hours after eating, not immediately. High-fat, high-protein meals — pizza, pasta with cream sauce, burgers — delay gastric emptying, meaning carbs from the meal are still entering the bloodstream 3–4 hours after eating.

If your child had pizza for dinner and their blood sugar is 280 at 10pm, the most likely explanation is delayed carb absorption, not a missing correction dose.

What to do: A correction dose is appropriate, but be cautious about stacking too much insulin — a portion of the meal may still be absorbing. Check again in 90 minutes before considering another correction.

Also consider: did your child eat something you didn’t know about? School snacks, a birthday treat they didn’t mention, juice from a friend’s lunchbox — these are common in school-age children and not necessarily dishonest, just forgotten or unreported.

4. Illness, stress, or hormonal activity

Illness dramatically raises blood sugar even if your child isn’t eating. Fever, infection, and inflammatory responses trigger stress hormones (cortisol, glucagon, adrenaline) that raise blood glucose regardless of food intake. A common cold can push blood sugar to 300+ in a child who is usually well-controlled.

Sick day rules exist for this reason: when your child is unwell, insulin requirements increase, not decrease — even if they’re not eating. This is counterintuitive for parents who worry about giving insulin without food.

Growth hormones and puberty are a less-discussed cause of persistent highs. During puberty, growth hormone secretion (heaviest at night) causes significant insulin resistance. Adolescents often need 30–50% more insulin than pre-pubescent children for the same food intake — and that need can appear to emerge suddenly.

Stress before a test, after a difficult social situation, or during an anxiety period also raises blood glucose via cortisol release.

5. Insulin has expired or been damaged

Check the expiration date and the storage history of your insulin. Rapid-acting insulin:

• Should be kept refrigerated until opened
• Once opened, is stable at room temperature for 28–30 days (check your brand’s specific instructions)
• Must not be frozen (destroys the molecule)
• Must not be left in heat above 77°F / 25°C

If you’re unsure whether insulin is effective, a new vial from a fresh refrigerated supply is the fastest way to test the hypothesis.

The Step-by-Step Decision Tree

Blood sugar above target and not coming down after one correction:

1. Check ketones
2. Inspect injection site / pump site
3. Review what was eaten in the past 3–4 hours
4. Check insulin integrity and expiration
5. Give correction at a fresh site (or by injection if on pump)
6. Hydrate — water, not juice or sugary drinks
7. Recheck in 90 minutes

Still not coming down after two corrections:

• Call your diabetes team’s after-hours line
• Continue checking ketones every hour
• Keep your child drinking water
• Do not give a third stacked correction without guidance unless ketones are rising and you cannot reach your team

When to Go to the Emergency Room

Go immediately — don’t call first — if:

• Blood sugar is above 300 mg/dL and your child is vomiting
• Blood or urine ketones are large/high and rising
• Your child is confused, drowsy, or difficult to rouse
• Your child is breathing rapidly or has fruity-smelling breath (sign of DKA)
• Blood sugar has been above 300 for more than 4 hours despite corrections

DKA (diabetic ketoacidosis) is a medical emergency. A 2011 study in Archives of Disease in Childhood found that DKA at presentation carries significant risk of cerebral edema, particularly in children under 5. The threshold for going to the ER should be low.

Building a Written Sick Day Plan

Ask your endocrinology team for a written sick day protocol at your next appointment. This should include:

• Specific ketone thresholds that trigger a call to the team
• Guidance on increasing basal insulin or long-acting dose during illness
• A correction scale (what dose to give at what blood sugar level)
• After-hours contact information
• The criteria that mean “go to the ER now, don’t call first”

Having this written down before you need it — and reviewing it when your child is well — means you’re not trying to remember instructions at 1am when blood sugar is 320 and you haven’t slept.