Tests used to diagnose diabetes
| Test | Normal | Pre-diabetes | Diabetes |
|---|
| Fasting Blood Glucose | <100 mg/dL (<5.6 mmol/L) | 100–125 mg/dL | ≥126 mg/dL on 2 occasions |
| Post-meal (2hr OGTT) | <140 mg/dL (<7.8 mmol/L) | 140–199 mg/dL | ≥200 mg/dL |
| HbA1c | <5.7% | 5.7–6.4% | ≥6.5% on 2 occasions |
| Random Blood Glucose | <140 mg/dL | — | ≥200 mg/dL with symptoms |
HbA1c — the most important diabetes test
What is HbA1c?
HbA1c (glycated haemoglobin) reflects your average blood sugar over the past 2–3 months. Unlike a single fasting glucose reading which only shows one moment in time, HbA1c gives a fuller picture. Sugar in the blood binds to haemoglobin in red blood cells — the more sugar, the higher the HbA1c. It's used both to diagnose diabetes and to monitor how well blood sugar is controlled in people already on treatment. A target HbA1c below 7% is generally recommended for most diabetic adults, though your doctor may personalise this target.
OGTT — Oral Glucose Tolerance Test
When is OGTT done?
The Oral Glucose Tolerance Test (OGTT) is the most sensitive test for detecting diabetes and pre-diabetes. You fast overnight, have a fasting blood glucose taken, then drink a solution containing 75g of glucose. Your blood glucose is checked again at 2 hours. It's particularly useful for: diagnosing gestational diabetes in pregnancy (usually at 24–28 weeks), detecting pre-diabetes not picked up by fasting glucose, and confirming borderline results.
Tests to monitor diabetes complications
Diabetes affects many organs over time. The following tests should be done at least annually in people with diabetes:
Kidney monitoring
| Test | Target for diabetics | What it checks |
|---|
| eGFR / Creatinine | eGFR >60 | Kidney filtering ability |
| Urine ACR (albumin:creatinine ratio) | <30 mg/g | Earliest sign of diabetic kidney damage |
| Urine Routine | No protein / glucose | General kidney health screen |
Cholesterol / cardiovascular monitoring
| Test | Target for diabetics | Why it matters |
|---|
| LDL Cholesterol | <70 mg/dL (high-risk) or <100 mg/dL | Main statin target — diabetes doubles heart risk |
| Triglycerides | <150 mg/dL | High in poorly controlled diabetes |
| HDL Cholesterol | Men >40; Women >50 mg/dL | Protective — low HDL = higher heart risk |
Other important checks
| Test / Exam | Frequency | Why |
|---|
| Blood pressure | Every visit | Target <130/80 mmHg in diabetes |
| Eye exam (fundoscopy) | Yearly | Diabetic retinopathy — silent until advanced |
| Foot examination | Yearly (or more often) | Peripheral neuropathy and ulcer risk |
| TSH (thyroid) | At diagnosis and periodically | Thyroid disease is more common in diabetics |
| Vitamin B12 | Yearly if on metformin | Metformin reduces B12 absorption |
Annual diabetes health checklist
- HbA1c — every 3–6 months until stable, then every 6 months
- Fasting lipid profile (cholesterol) — annually
- Kidney function: eGFR + urine ACR — annually
- Eye examination (diabetic retinopathy screen) — annually
- Foot examination — annually
- Blood pressure check — every visit
- Vitamin B12 if on metformin — annually
- TSH — at diagnosis and every 1–2 years
- Dental check — 6-monthly (gum disease is worse in diabetes)
Target blood sugar ranges for people with diabetes
| Time of day | Target (mg/dL) | Target (mmol/L) |
|---|
| Fasting / before meals | 80–130 | 4.4–7.2 |
| 2 hours after meals | <180 | <10.0 |
| Bedtime | 100–140 | 5.6–7.8 |
| HbA1c target | <7% (individualised) | — |
Questions to ask your diabetes doctor
- What is my HbA1c target?
- Do I have any early kidney damage (urine ACR)?
- When did I last have my eyes checked?
- Should I be on a statin for heart protection?
- Is my metformin affecting my Vitamin B12?
- Am I eligible for newer diabetes drugs (GLP-1 or SGLT2 inhibitors) that protect the heart and kidneys?
Medical Disclaimer: This page is for general educational purposes only. Diabetes management should always be done under the guidance of a qualified healthcare professional. Blood sugar targets may be personalised based on individual circumstances.