Clinical Reference Matrix

Blood Sugar Chart

Reference the official clinical diagnostic thresholds for fasting blood glucose, post-meal readings, and random testing in both mmol/L and mg/dL.

Diagnostic Blood Sugar Thresholds

Standard venous and capillary glucose targets used for screening and monitoring. (Values displayed in mmol/L (standard) 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
HbA1c (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

Low blood sugar requires immediate carbohydrate intake to prevent neuroglycopenic symptoms and loss of consciousness:

Level 1 Hypoglycaemia

3.0–3.8 mmol/L (54–69 mg/dL)

Consume 15g of fast-acting glucose (e.g. 150ml fruit juice, 3–4 jelly babies). Re-check in 15 minutes (Rule of 15).

Level 2 Hypoglycaemia

< 3.0 mmol/L (< 54 mg/dL)

Immediate action required. Consume rapidly absorbable carbohydrates; seek assistance if cognitive confusion begins.

Level 3 Hypoglycaemia (Severe)

Variable (Severe cognitive impairment)

Medical emergency. Requires assistance from another person. Administer emergency glucagon; dial 999 immediately if unconscious.

Natural nocturnal release of cortisol, growth hormone, and glucagon between 4 AM and 8 AM stimulates hepatic glucose release.

Infections, fever, acute pain, or surgery trigger adrenaline and systemic inflammation that significantly elevate circulating glucose.

Systemic corticosteroids (prednisone), certain beta-blockers, and thiazide diuretics can artificially raise blood sugar levels.