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Understanding hyperglycaemia

A big meal, a stressful afternoon, or even skipping a walk can sometimes cause highs to happen. They’re part of life with diabetes, but they don’t mean you’ve done anything wrong.

a man eating in a restaurant and a FreeStyle Libre sensor is visible on his arm a man eating in a restaurant and a FreeStyle Libre sensor is visible on his arm a man eating in a restaurant and a FreeStyle Libre sensor is visible on his arm

What is hyperglycaemia?

Hyperglycaemia, or “highs,” simply means your glucose has built up too much in the bloodstream1. This happens when your body doesn’t have enough insulin or can’t use it efficiently to move glucose into your cells for energy1.

a man is adding milk to his drink and a freestyle libre sensor is visible on his arm a man is adding milk to his drink and a freestyle libre sensor is visible on his arm a man is adding milk to his drink and a freestyle libre sensor is visible on his arm


What causes hyperglycaemia?

Highs can happen without warning, even when you’re doing your best. That’s why it’s important to understand what may cause them and how they might feel in your body. Consult with your doctor about other potential causes of highs.



Causes of highs2.

  • Eating more carbohydrates than your body can process

  • Changes in your physical activity

  • Stress, illness, or even poor sleep

  • Missed medication or medication not suited to your needs

  • Dawn phenomenon (rise in glucose that happens in the morning)3

 

a woman applying her makeup and a FreeStyle Libre sensor is visible on her arm a woman applying her makeup and a FreeStyle Libre sensor is visible on her arm

What are the symptoms of hyperglycaemia?

You might not notice symptoms until levels rise above 10–11.1 mmol/L4, and for some, they appear closer to 13.9 mmol/L2.

  • Headaches2

  • Frequent urination2

  • Feeling very hungry or thirsty2

  • Blurry vision2

Some people don't feel symptoms at all.

 

Stay ahead of highs, with a little help from the FreeStyle Libre 2 system or FreeStyle Libre 3 system.
 

Through graphs, trend arrows, and alarms, the FreeStyle Libre 2 system or FreeStyle Libre 3 system lets you know when glucose levels are rising so you can take action before levels rise too far¤.

How to prevent highs2.

an image of a pill icon an image of a pill icon

Follow your care plan and take medications as prescribed by your healthcare professional

an image of a glucose graph icon an image of a glucose graph icon

Check your levels when you notice signs of a rise

an image of a food icon an image of a food icon

Pair carbs with protein or fibre for steadier energy

an image of a water icon an image of a water icon

Drink water and move when you can

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Notice which meals or moments lead to higher readings and adjust over time

Preventing highs¤, one reading at a time.

The ups and downs in your continuous glucose readings will start to tell a story over time.

Maybe you’ll notice your glucose rises after certain meals or dips with a walk after dinner. The more you track, the more you understand what keeps you steady.

a man looking at his glucose data on his phone a man looking at his glucose data on his phone a man looking at his glucose data on his phone
an image of a decrease icon an image of a decrease icon

Quick tip: Check your trend arrow.  

Check the arrow to the right of your current glucose reading. Is it pointing straight up, or upward to the right?

When glucose levels are rising beyond your safe range, it might be time to take action. That could mean a short walk, a glass of water, or taking your medication as planned.

Those small, steady actions add up to balance—and that’s what progress looks like.

Further reading

Understanding hypoglycaemia

⏱ 3 minutes read

Discover what hypoglycaemia is and how to prevent it from happening.

Learn more

Triangle of Diabetes Care

⏱ 5 minutes read

Stay in control by tracking the three pillars of diabetes care with the FreeStyle Libre system.*

Read article here

References & Disclaimers

Images are for illustrative purposes only. Not real patients or data.

1. American Diabetes Association. “Hyperglycemia.” American Diabetes Association.
https://diabetes.org/living-with-diabetes/treatment-care/hyperglycemia.  (Last accessed: April 2026)

2. Cleveland Clinic. “Hyperglycemia (High Blood Sugar).” Cleveland Clinic.
https://my.clevelandclinic.org/health/diseases/9815-hyperglycemia-high-blood-sugar.  (Last accessed: April 2026)

3. Lavin-Tompkins, Jodi. "Dawn Phenomenon vs. Somogyi Effect: Morning High Blood Sugars Explained." Beyond Type 1. July 30, 2020. https://beyondtype1.org/dawn-phenomenon-vs-somogyi-effect-morning-high-blood-sugars-explained/.

4. Mayo Clinic. “Hyperglycemia in diabetes.” Mayo Clinic.  https://www.mayoclinic.org/diseases-conditions/hyperglycemia/symptoms-causes/syc-20373631.  (Last accessed: April 2026)

¤ Notifications will only be received when alarm settings are enabled and turned on and the sensor is within [20 feet or 6 metres] (FreeStyle Libre 2 system) or [33 feet or 10 metres] (FreeStyle Libre 3 system) of the reading device, unobstructed.

ADC-131352 v1.0
 

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