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When there isn’t enough insulin in your body, or when the hormone becomes ineffective, your cells are unable to use the available glucose, which then builds up in the blood.

Hyperglycemia occurs when glucose levels rise above target values, i.e.:

  • Over 7 mmol/L fasting or before a meal
  • Over 10 mmol/L two hours after a meal

Chronic hyperglycemia is what causes the long-term complications of diabetes such as blood vessel and nerve damage, blindness and kidney failure.


  • Fatigue or drowsiness
  • Dizziness
  • Irritability
  • Exaggerated hunger
  • Intense thirst
  • Dry mouth
  • Frequent need to urinate or abundant urine

Sounds familiar? It should: type 2 diabetes manifests through hyperglycemia.


Hyperglycemia occurs when there is an imbalance between diet, physical activity and medication or insulin doses.

Maybe you ate more food or carbs than usual, or your workout may have been cut short? You may also have taken too little insulin or, in the case of type 2 diabetes, taken the right dose of insulin, which wasn’t as effective as it should have been.

Psychological or physical stress (illness, infection, etc.) or certain medications, such as cortisone, can also affect blood sugar levels.

How to prevent it

  • Monitor your blood sugar closely.
  • Follow the diet plan developed by your nutritionist or dietitian.
  • Adjust your insulin dose based on your diet and activities, and recalculate the amount of insulin you need when necessary.
  • Take your medication as prescribed by your physician.

The “dawn phenomenon”

Everyone experiences a surge of hormones before they wake up. The cocktail of adrenaline, cortisol and growth hormone promotes glucose secretion by the liver.

In people living with diabetes, the pancreas doesn’t produce enough insulin to regulate the resulting increase in blood glucose. This “dawn phenomenon” can lead to hyperglycemia, even if blood glucose levels were at target values at bedtime.

Eating earlier in the evening or exercising after dinner can help correct the situation.

What to do in case of hyperglycemia

Drink enough water to avoid dehydration.

Measure your blood glucose more frequently to identify the cause of the problem. You can then adjust your diet or physical activity schedule, or consult your physician to have your medication or insulin dose adjusted.

It is a medical emergency if the person:

- Does not tolerate any fluid or shows signs of dehydration (e.g., if they are nauseous or vomiting)

- Displays an altered state of consciousness—is confused or agitated, engages in unusual behaviour, has hallucinations or fails to respond to stimuli

- Has a body temperature above 38.5°C for more than 48 hours

In the case of type 1 diabetes, if blood glucose levels are above 14 mmol/L, check for the presence of ketones: if a medium to high level of ketone bodies are present (over 4 mmol/L in urine or over 1.5 mmol/L in blood), see a health care professional. It is also worth consulting if someone with type 2 diabetes has a blood glucose level above 25 mmol/L and is excessively drowsy.

In conclusion

By being vigilant and learning to understand your body’s reactions, you can help prevent problems and manage diabetes more comfortably!


American Diabetes Association, “Hyperglycemia (High Blood Glucose)”: Accessed January 27, 2017.
American Diabetes Association, “Dawn Phenomenon”: Accessed January 27, 2017.
Canadian Diabetes Association, “Lows & highs: Blood sugar levels”: Accessed January 25, 2017.
Diabetes Québec, “The Dawn Phenomenon”: Accessed January 27, 2017.
Diabetes Québec, “Hyperglycemia”: Accessed January 27, 2017.
Fédération française des diabétiques, “Comment faire face à l’hyperglycémie?”: Accessed January 27, 2017.
Mayo Clinic, “Hyperglycemia in diabetes”: Accessed January 27, 2017.
WebMD, “High Blood Sugar and Diabetes”: Accessed January 27, 2017.

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