Diabetes Basics: Understanding Your Numbers (FBS, RBS, HbA1c)
By Pharmacist Saini Kennedy L.

Diabetes is a condition where blood sugar (glucose) stays higher than normal. The good news: when you understand your key numbers and monitor them correctly, you can reduce symptoms and prevent long-term complications affecting the eyes, kidneys, nerves, heart, and feet. This guide explains the most common tests you’ll hear about; FBS, RBS, and HbA1c and general targets, monitoring tips, and when to seek care.

1) The three key numbers

A. FBS (Fasting Blood Sugar)
What it is: Your blood glucose after at least 8 hours with no calories (water is allowed).
Why it matters: It reflects your “baseline” glucose control and is often used for diagnosis and monitoring.

General interpretation (adults, non-pregnant):
Normal: <5.6 mmol/L
Prediabetes: 5.6–6.9 mmol/L
Diabetes: ≥7.0 mmol/L on a test (usually confirmed on a separate day)

B. RBS (Random Blood Sugar)
What it is: A blood glucose reading taken at any time, regardless of meals.
Why it matters: It’s useful when someone has symptoms and needs a quick check.

General interpretation:
Diabetes is likely if RBS is ≥ 11.1 mmol/L plus symptoms (e.g., excessive thirst, frequent urination, unexplained weight loss, blurred vision).

C. HbA1c (Glycated Hemoglobin)
What it is: A blood test that estimates your average blood glucose over the last ~2–3 months.
Why it matters: It shows longer-term control—not just a “one-day” reading.

General interpretation:
Normal: < 5.7%
Prediabetes: 5.7–6.4%
Diabetes: ≥6.5%

Note: HbA1c may be less reliable in some conditions (e.g., certain anemias/hemoglobin disorders, recent major blood loss/transfusion, pregnancy). Ask your clinician/pharmacist if this applies to you.

2) Targets: what numbers should you aim for?
Targets are individualized based on age, pregnancy, other medical conditions, and risk of low blood sugar. The ranges below are common adult, non-pregnant goals used in many guidelines.

Common day-to-day glucose targets
Fasting / before meals: 4.4–7.2 mmol/L
1–2 hours after meals (post‑meal): < 10.0 mmol/L

HbA1c target
For many non-pregnant adults: < 7%
Some people may need a stricter or less strict target—this should be decided with your clinician.

3) Monitoring: how often should you check?
Monitoring depends on your diabetes type and treatment.

If you use insulin
You may need checks multiple times daily (before meals, sometimes after meals, at bedtime, and when you feel “low” or unwell).

If you use tablets only (and no insulin)
Your clinician may recommend checking a few times per week, or doing “paired testing” (before and 2 hours after a meal) on certain days to see how food affects you.

If you are newly diagnosed, changing treatment, or sick
You usually need more frequent checks until stable.

Practical monitoring tips
Wash and dry hands before testing (sugar residue can falsely raise results).
Use the same meter consistently and ensure strips are not expired.
Keep a simple record: date/time, reading, meal/medicine, symptoms, exercise.
If you can, bring your meter/logbook to the pharmacy or clinic for review.

4) When to seek care urgently (don’t wait)

Seek urgent medical care if you have:
Blood glucose ≥ 16.7 mmol/L repeatedly, especially with symptoms
Signs of dehydration: very dry mouth, dizziness, confusion
Vomiting, severe abdominal pain, deep/fast breathing, fruity breath (possible ketoacidosis, especially in type 1 diabetes)
Drowsiness/confusion or fainting
Fever or infection with poor intake and persistently high sugars

Treat as an emergency (possible low blood sugar) if:
You feel shaky, sweaty, confused, very hungry, weak, or have palpitations and your glucose is low (often < 3.9 mmol/L), or you can’t test but symptoms are strong.
If unconscious or unable to swallow: seek emergency help immediately (do not give food/drink).

Seek prompt review (within days) if:
Fasting sugars are consistently above your target; 7.2 mmol/L
Post‑meal sugars are frequently high; 10 mmol/L
You have repeated lows, especially at night
You have symptoms of high sugar: thirst, frequent urination, blurred vision, recurrent infections
Foot problems: numbness, wounds, colour changes, swelling, pain

5) What else matters besides numbers?
Good diabetes care includes:
Blood pressure control
Cholesterol management
Healthy lifestyle; eating, weight management, regular physical activity
Foot care and eye checks
Taking medicines consistently (adherence) and reviewing side effects

Your pharmacist can help with: medication timing, avoiding interactions, insulin storage, injection technique, glucose meter use, and building a simple monitoring plan.

Quick summary
FBS checks fasting sugar control; RBS is a quick anytime reading; HbA1c shows the 2–3 month average.
Common targets: 4.4-7.2 mmol/L fasting, <10 mmol/L after meals, HbA1c <7% for many adults.
Seek urgent care for very high readings with illness symptoms or for severe low blood sugar symptoms.

If you need a blood sugar monitoring machine or need help interpreting your results or setting safe targets, visit SYLKay Pharmacies for guidance and support.

References
1. American Diabetes Association. Standards of Care in Diabetes—2025. Diabetes Care. 2025. (Glycemic targets; diagnosis criteria; monitoring recommendations).
2. World Health Organization (WHO). Use of glycated haemoglobin (HbA1c) in the diagnosis of diabetes mellitus. WHO guideline/technical document, 2011.
3. International Diabetes Federation (IDF). IDF Diabetes Atlas (latest edition). International Diabetes Federation. (General diabetes information and global guidance).
4. National Institute for Health and Care Excellence (NICE). Type 2 diabetes in adults: management (NG28). NICE guideline (updated regularly).
5. Centers for Disease Control and Prevention (CDC). Diabetes testing and A1C information (patient education resource; interpretation and basics).

This is educational content only; not a substitute for individualised medical advice. Targets and monitoring frequency should be personalised by a qualified clinician.