Everyone with Type 1 diabetes experiences high blood sugar sometimes — even with excellent care. It can happen on busy days, during illness, after exciting events, during growth spurts, or just “because diabetes felt like it today.”
This guide explains what high blood sugar is, why it happens, how it feels, and what to do — in a calm, confidence-building way for families, schools, and workplaces.
What Is High Blood Sugar?
High blood sugar (hyperglycaemia) means glucose is above the recommended range. For many people with Type 1, this means above 10 mmol/L, though exact targets vary. I class anything over 7 as high, but that's just my preference.
Everyone with Type 1 diabetes experiences high blood sugar sometimes — even with excellent care. It can happen on busy days, during illness, after exciting events, during growth spurts, or just “because diabetes felt like it today.”
This guide explains what high blood sugar is, why it happens, how it feels, and what to do — in a calm, confidence-building way for families, schools, and workplace.
Think of it like a traffic light:
✅ Safe range: Green
⚠️ Rising: Amber — check, hydrate, adjust
🚨 High or high with ketones: Red — take action
One high reading does not cause harm. It’s the pattern and how it’s treated that matters.
Why High Blood Sugar Happens
There are many possible causes — and none mean someone has “done badly.” Diabetes is influenced by dozens of variables, including things we can’t see.
Common causes
Not enough insulin given
Carb count miscalculated (easy to do!)
Growth spurts or puberty
Stress, worry, excitement, adrenaline (this can include resistance work in the gym)
Illness or infection
Periods or hormone changes
Pump site issues or tubing kinked
Insulin pen not primed / needle blocked
Insulin spoiled by heat or freezing
Skipped/pre-bolus delayed
Eating later than planned
Child-specific triggers
Busy play and forgetting symptoms
Emotional swings at school or home
Hugely variable activity levels day to day
Big feelings after school days (aka “after-school spike”)
Adult-specific triggers
Work stress
Travel and disrupted routine
Missed bolus while multitasking
Alcohol wearing off overnight
“Highs don’t mean failure — they mean your body asked for a little support.”
How High Blood Sugar Can Look From the Outside
People observing may notice:
Frequent drinking or asking for water
Needing the toilet often
Looking tired or washed out
Irritability or mood swings
Difficulty concentrating or answering questions
Headache or rubbing eyes
Flushed face
Fast breathing or frequent sighing
Children might:
Become emotional or grumpy
Ask to sit down or stop playing
Say their tummy hurts
Struggle with schoolwork suddenly
Appear unusually quiet or clingy
None of these behaviours are deliberate — the body is working hard.
How High Blood Sugar Feels on the Inside
Everyone’s experience is different, but common symptoms include:
Thirst or dry mouth
Headache
Feeling hot or flushed
Tiredness or energy crash
Trouble focusing (“brain fog”)
Blurry vision or stinging eyes
Nausea or tummy ache
Feeling heavy, slow, or weighed down
Irritable or emotional
Kids may say:
“My body feels sticky”
“My head hurts”
“I feel too tired”
“I’m thirsty again”
“Everything feels slow”
Again — not misbehaviour. Physical discomfort.
What To Do When Blood Sugar Is High
✅ Step 1: Check glucose & ketones
Especially if:
Blood sugar is above 13 mmol/L
Feeling unwell
Pump user with unexplained high
Vomiting or stomach pain
✅ Step 2: Correct with insulin
Use your prescribed correction ratio.
Do not “guess extra” insulin — corrections add up quickly.
✅ Step 3: Drink water
Helps clear glucose and ketones.
✅ Step 4: Check infusion set / pen / insulin
If using a pump, inspect for:
Bent cannula
Loose adhesive
Bubbles
Tubing disconnect
If in doubt, change the site.
Pen users: consider priming and checking insulin freshness.
✅ Step 5: Move gently — but only if NO ketones
Walking, light play, slow cycling, stretching
No hard exercise with ketones — can worsen levels.
✅ Step 6: Re-check in 2 hours
Follow diabetes team advice for dose spacing.
When To Check Ketones
Check if:
Above 13 mmol/L for 2 readings
Feeling sick or in pain
Tiredness/excessive thirst
Unexpected high with pump
Vomiting
Breathing fast or fruity breath
Ketones mean the body needs insulin — and plenty of fluids.
DKA Warning Signs — Emergency
Call emergency help if:
🚨 Fast breathing
🚨 Fruity smell on breath
🚨 Severe tummy pain or vomiting
🚨 Confusion or extreme tiredness
🚨 Unable to keep fluids down
🚨 High ketones despite insulin
This can develop quickly, especially in children.
How Others Can Support
Parents, teachers, and carers can:
Stay calm — tone matters
Offer water
Provide a quiet space if the child feels unwell
Never shame or blame
Encourage a re-check
Help check pump site if appropriate
Keep snacks, insulin supplies, spare cannulas available
Use gentle language like:
“Let’s help your body get back in balance.”
At school: allow water, toilet breaks, and rest without question.
Helping Kids Build Confidence
Encourage them to:
Speak up when they feel high
Ask for water or a rest
Pause play if needed
Carry supplies proudly — it’s strength, not weakness
A supportive environment makes children brave and independent.
Preventing Highs Where Possible
Dose insulin before meals when safe
Maintain working insulin pens/pump sites
Keep backup supplies and spares
Learn patterns (CGM data helps)
Hydrate throughout the day
Adjust doses during illness (as advised)
Seek emotional support — stress affects glucose too
Even with all this, highs still happen.
And that’s okay.
A Kind, Gentle Final Note
Living with Type 1 diabetes means adjusting, learning, and adapting every single day. No one — not adults, not parents, not kids — gets it right 100% of the time.
Highs do not mean:
❌ Failure
❌ Neglect
❌ “Bad control”
❌ Poor effort
They mean the body asked for help — and with support, you gave it.
You are doing an amazing job. Truly.
Disclaimer
This blog is for education and support only, not medical advice. Always follow your diabetes care team's guidance. Seek urgent medical help if severe symptoms, vomiting, or high ketones occur.