Blood Sugar Numbers: What They Mean and What Your Target Should Be

You’ve bought a glucometer. You’re testing your blood sugar. But now you’re staring at a number — 8.4 mmol/L — and you have no idea if that’s good, bad, or somewhere in between. You’re not alone. This is one of the most common confusions among people newly diagnosed with diabetes.

Let’s fix that today. Here’s everything you need to know about blood sugar numbers.

The Two Units: mmol/L and mg/dL

Blood sugar is measured in two different units depending on where you are in the world:

• mmol/L (millimoles per litre) — used in Ghana, Nigeria, UK, Canada, and most of Africa
• mg/dL (milligrams per decilitre) — used in the USA and some other countries

To convert: multiply mmol/L by 18 to get mg/dL. So 7.0 mmol/L = 126 mg/dL.

Normal Blood Sugar Ranges (for people without diabetes)

• Fasting (before eating): 3.9 – 5.5 mmol/L (70 – 99 mg/dL)
• 2 hours after eating: Less than 7.8 mmol/L (less than 140 mg/dL)

Target Ranges for People With Diabetes

• Fasting / before meals: 4.0 – 7.0 mmol/L (72 – 126 mg/dL)
• 2 hours after meals: Less than 10.0 mmol/L (less than 180 mg/dL)
• Bedtime: 5.0 – 8.3 mmol/L (90 – 150 mg/dL)

These are general targets. Your doctor may give you personalised targets based on your age, other health conditions, and diabetes type.

When Is Blood Sugar Too Low? (Hypoglycaemia)

Blood sugar below 3.9 mmol/L (70 mg/dL) is considered low (hypoglycaemia). This is a medical emergency if severe. Symptoms include:

• Shakiness or trembling
• Sweating
• Rapid heartbeat
• Confusion or difficulty concentrating
• Dizziness or fainting

If your sugar drops below 3.9 mmol/L: immediately eat or drink something with fast-acting sugar — 3-4 glucose tablets, half a cup of fruit juice, or a few pieces of candy. Check again after 15 minutes.

When Is Blood Sugar Too High? (Hyperglycaemia)

Blood sugar consistently above 10.0 mmol/L (180 mg/dL) after meals, or above 7.0 mmol/L (126 mg/dL) fasting, needs attention. If it stays very high (above 13.9 mmol/L / 250 mg/dL), contact your doctor immediately.

What Is HbA1c and Why Does It Matter?

Your daily readings show your blood sugar at one point in time. Your HbA1c (glycated haemoglobin) shows your average blood sugar over the past 2-3 months — a much better picture of your overall control.

• Normal (no diabetes): Below 5.7%
• Pre-diabetes: 5.7% – 6.4%
• Diabetes diagnosis: 6.5% or above
• Well-controlled diabetes: Below 7.0%

The Mina AI app estimates your HbA1c based on your recent blood sugar readings — so you always have a sense of where you stand between doctor visits.

How Often Should You Test?

This depends on your treatment plan. General guidance:

• On insulin: Test before meals, 2 hours after meals, and at bedtime — at minimum 4 times daily
• On oral medication: Test fasting each morning, and 2 hours after your largest meal
• Diet-controlled: Test fasting and after meals 2-3 times per week to track patterns

The most important thing is consistency. Regular testing helps you and your doctor see what’s working and what needs adjustment.