Blood Sugar Chart
Reference official clinical diagnostic thresholds for fasting blood glucose, post-meal readings, and random testing in Canadian standard units (mmol/L) and mg/dL.
Diagnostic Blood Sugar Thresholds
Standard venous and capillary glucose targets used for screening and monitoring in Canada. (Values displayed in mmol/L and mg/dL.)
| Testing Context | Normal Range | Prediabetes Window | Diabetes Diagnostic |
|---|---|---|---|
| Fasting (no food for ≥ 8 hours) | 70–99 mg/dL 3.9–5.5 mmol/L | 100–125 mg/dL 5.6–6.9 mmol/L | 126 mg/dL or higher 7.0 mmol/L or higher |
| 2 Hours After Meals (Postprandial) | < 140 mg/dL < 7.8 mmol/L | 140–199 mg/dL 7.8–11.0 mmol/L | 200 mg/dL or higher 11.1 mmol/L or higher |
| Bedtime / Overnight | 90–120 mg/dL 5.0–6.7 mmol/L | 120–140 mg/dL 6.7–7.8 mmol/L | > 140 mg/dL > 7.8 mmol/L |
| Hemoglobin A1C (3-month avg) | < 5.7% < 39 mmol/mol | 5.7% – 6.4% 39–46 mmol/mol | 6.5% or higher 48 mmol/mol or higher |
Hypoglycemia (Low Blood Sugar) Action Levels
Low blood sugar requires immediate carbohydrate intake to prevent neuroglycopenic symptoms and loss of consciousness:
Consume 15g of fast-acting glucose (125ml fruit juice, 3–4 glucose tablets). Re-check in 15 minutes (Rule of 15).
Immediate action required. Consume rapidly absorbable carbohydrates; seek assistance if cognitive confusion begins.
Medical emergency. Requires assistance from another person. Administer emergency glucagon; call 911 immediately if unconscious.
Factors That Cause Temporary Glucose Spikes
Dawn Phenomenon
Natural nocturnal release of cortisol, growth hormone, and glucagon between 4 AM and 8 AM stimulates hepatic glucose release.
Physical Stress & Illness
Infections, fever, acute pain, or surgery trigger adrenaline and systemic inflammation that significantly elevate circulating glucose.
Medication Interactions
Systemic corticosteroids (prednisone), certain beta-blockers, and thiazide diuretics can artificially raise blood sugar levels.