Understanding your blood sugar numbers is the first step in managing diabetes and preventing long-term complications. “Good control” isn’t a one-size-fits-all number; it is a personalized target set by you and your doctor.
Medical professionals use two primary tests to diagnose Diabetes and Prediabetes: Blood Glucose (a snapshot of right now) and HbA1c (your 3-month average).
1. Blood Glucose Levels (Snapshot)
| Status | Fasting Glucose | Random/Post-Meal Glucose |
| Normal | 4.0–6.0 mmol/L | Under 7.8 mmol/L |
| Prediabetes | 6.1–6.9 mmol/L | 7.0–11.0 mmol/L |
| Diabetes | > 7.0 mmol/L | > 11.1 mmol/L |
2. HbA1c Levels (3-Month Average)
The HbA1c test measures the percentage of glucose attached to your red blood cells.
Normal: 20–42 mmol/mol (4%–6%)
Prediabetes: 42–47 mmol/mol (6%–6.5%)
Diabetes: 48 mmol/mol or over (6.5%+)
Once diagnosed, “Good Diabetic Control” means keeping your levels within a specific range to prevent damage to your heart, kidneys, and eyes. The American Diabetes Association (ADA) and NICE (UK) generally recommend these targets for most adults:
Fasting Blood Glucose: 4–7 mmol/L (72–126 mg/dL)
Post-Meal (2 hours after eating): 5–10 mmol/L (90–180 mg/dL)
HbA1c Target: < 48 mmol/mol (< 6.5%) for many, though some doctors aim for < 53 mmol/mol (7.0%).
Health is individual. Your doctor may adjust your targets based on your age, lifestyle, and other health conditions.
When Higher Targets are Safer
For some, aiming for “Normal” levels can actually be dangerous.
The Elderly: A target of 7–12 mmol/L may be safer for older patients.
Hypoglycaemia Risk: The danger of a “hypo” (low blood sugar) leading to a fall or confusion is often more life-threatening than the long-term risks of slightly higher blood sugar.
Clinical Duration: If you have lived with diabetes for 20+ years, your body may require a more relaxed target to avoid cardiovascular stress.
Factors that Change Your Target:
Age: Younger patients often have stricter targets to prevent complications over decades.
Comorbidities: Heart disease or kidney disease (CKD) may change your medication and target.
Pregnancy: Targets are significantly stricter during pregnancy to protect the baby.
Test Regularly: Use a glucose monitor to see how different foods affect you.
Know Your HbA1c: Have this blood test at least twice a year – 4x a year if control is not good.
Consult Your Team: Never change your medication dosage without speaking to your GP or Diabetic Nurse.
Important Note: If your blood sugar consistently exceeds 15 mmol/L, contact your doctor, as this may lead to Diabetic Ketoacidosis (DKA), a medical emergency.
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