Understanding Your Blood Sugar

What is normal blood sugar?

Blood sugar is measured in millimoles per litre (mmol/L). For people without diabetes, blood sugar usually stays between 4.0 and 6.0 mmol/L. If you have diabetes, the targets are slightly wider — but the closer to normal values you are, the better for your health.

Time of day	Target for most with diabetes	Without diabetes (reference)
Fasting / morning	4.0–7.0 mmol/L	3.9–5.6 mmol/L
Before meals	4.0–7.0 mmol/L	3.9–5.6 mmol/L
2 hours after eating	Below 10.0 mmol/L	Below 7.8 mmol/L
At bedtime	6.0–9.0 mmol/L	–

Remember:

Your targets may vary. Your doctor or diabetes care team will set individual goals based on your situation, age and any other conditions.

What affects blood sugar?

Factor	Effect on blood sugar
Carbohydrates in food	Raises (quickly or slowly depending on type)
Physical activity	Usually lowers (except high intensity)
Stress and illness	Raises (stress hormones are released)
Lack of sleep	Increases insulin resistance
Alcohol	Can lower significantly, especially next morning
Medication / insulin	Lowers (effect varies)
Hormonal cycle (women)	Can vary throughout the month

Low blood sugar – hypoglycaemia

Hypoglycaemia means blood sugar below 4.0 mmol/L. It is important to treat quickly.

Symptoms of low blood sugar:

● Trembling, sweating, rapid heartbeat
● Dizziness, headache
● Difficulty concentrating, irritability
● Hunger, paleness

If blood sugar is below 4.0 mmol/L:

Take 15 grams of fast carbohydrates — e.g. 3 glucose tablets, 150ml juice or 3 teaspoons of sugar. Recheck blood sugar after 15 minutes. Contact a doctor if you faint or have repeated episodes.

High blood sugar – hyperglycaemia

Hyperglycaemia means persistently high blood sugar, usually above 10 mmol/L. Without treatment it can lead to serious complications over time.

Symptoms of high blood sugar:

● Increased thirst and frequent urination
● Fatigue and reduced concentration
● Blurred vision
● Slow wound healing

Contact a doctor if:

Blood sugar is repeatedly above 15 mmol/L, or you have high blood sugar combined with nausea, vomiting or fruity breath — these may be signs of ketoacidosis requiring urgent medical attention.

Tips for stable blood sugar

✅ Monitor regularly – before and after meals to learn your own patterns
✅ Log your values – an app or notebook makes it easier to spot trends
✅ Eat at regular times – consistent meals give more stable blood sugar
✅ Walk after dinner – 20 minutes noticeably lowers blood sugar
✅ Share your log with your care team – it makes adjustments much easier