CHAPTER 23 — BLOOD TESTS: HOW TO READ YOUR RESULTS Blood tests are essential tools for understanding Type 2 Diabetes. They show how well glucose is controlled, whether organs are under strain, and whether treatment needs adjusting. This chapter explains each important test in simple language so you can understand your results and discuss them with your healthcare team. WHY BLOOD TESTS MATTER Blood tests help to:
- Detect problems early, before symptoms appear.
- Track improvements in glucose control.
- Adjust medication safely.
- Protect the kidneys, liver, heart, and blood vessels.
- Guide decisions about lifestyle changes.
Most tests are done once or twice per year, although some are more frequent. THE MAIN BLOOD TESTS FOR TYPE 2 DIABETES 1. HbA1c (A1C) — AVERAGE 3-MONTH GLUCOSE What it measures:
- The percentage of haemoglobin (red blood cells) with glucose attached.
What it shows:
- Your average glucose over the last 8–12 weeks.
Typical interpretation:
- Below 5.7%: usually normal.
- 5.7–6.4%: prediabetes range.
- 6.5% or above: diabetes range.
Target ranges vary by age, health, and individual risk. Ask your professional for your personal target. Why it matters:
- Higher A1C means more chance of complications.
- Lower A1C (safely achieved) protects eyes, kidneys, nerves, and heart.
Limitations:
- Can be misleading in anaemia or conditions affecting red blood cells.
- Does not show daily highs and lows.
2. FASTING GLUCOSE What it measures:
- Blood sugar after at least 8 hours with no calories.
Typical interpretation:
- Below 100 mg/dL (5.6 mmol/L): normal.
- 100–125 mg/dL (5.6–6.9 mmol/L): prediabetes.
- 126 mg/dL (7.0 mmol/L) or higher on two tests: diabetes.
Why it matters:
- Reflects liver glucose output overnight.
- Often the hardest number to improve due to hormones and liver fat.
3. POSTMEAL GLUCOSE What it measures:
- Blood sugar one to two hours after eating.
Why it matters:
- Shows how well your body handles carbohydrates.
- Helps identify foods that cause spikes.
- Helps tailor carbohydrate intake.
- High postmeal spikes increase risk of complications over time.
Targets vary; focus on improvement, not perfection. 4. KIDNEY FUNCTION TESTS a) Creatinine A waste product filtered by the kidneys. b) eGFR (estimated glomerular filtration rate) Shows how well the kidneys filter blood. Typical interpretation:
- Higher eGFR = better kidney function.
- Below 60 may indicate chronic kidney disease.
c) Urine albumin Checks for protein leakage due to early kidney damage. Why it matters:
- Early kidney issues often have no symptoms.
- Good glucose, blood pressure, and cholesterol control protect the kidneys.
- SGLT2 inhibitors (in some cases) offer kidney protection.
5. LIVER FUNCTION TESTS Important markers:
- ALT (alanine transaminase)
- AST (aspartate transaminase)
- GGT (gamma-glutamyl transferase)
What they show:
- Inflammation or fat in the liver.
- Alcohol effects.
- Impact of medications.
Why it matters:
- Fatty liver is common in Type 2 Diabetes.
- Reducing carbohydrates, sugar, and late eating can improve liver numbers.
6. CHOLESTEROL AND LIPID PANEL Key components:
- LDL (“bad” cholesterol)
- HDL (“good” cholesterol)
- Triglycerides
- Total cholesterol
Typical patterns in insulin resistance:
- High triglycerides.
- Low HDL.
- Small dense LDL particles.
Why it matters:
- Abnormal lipids increase risk of heart attack and stroke.
- Improving diet, activity, and weight usually helps.
- Medication may be advised depending on risk.
7. THYROID FUNCTION TESTS Key tests:
- TSH
- Free T4
- Free T3 (sometimes)
Why it matters:
- Thyroid issues can affect weight, energy, and glucose control.
- Fatigue or unexplained symptoms may require testing.
8. VITAMIN LEVELS Important ones include:
- Vitamin D
- Vitamin B12 (especially if on metformin)
- Iron studies (ferritin, iron, transferrin saturation)
Why it matters:
- Low vitamin D is linked with poorer metabolic health.
- Metformin can lower B12 levels over time.
- Iron imbalance can affect energy and glucose.
9. INSULIN AND C-PEPTIDE (ADVANCED TESTING) These are not routine but sometimes used to assess:
- Insulin resistance.
- Pancreatic insulin production.
- Whether insulin therapy might be needed.
C-peptide helps show how much insulin your pancreas still makes. HOW OFTEN SHOULD YOU TEST? General rhythm:
- A1C: every 3–6 months.
- Kidney and liver tests: yearly or as advised.
- Lipids: yearly.
- Thyroid: every 1–2 years or if symptoms appear.
- Vitamin levels: yearly for many adults.
- Postmeal glucose: whenever testing meals.
- Fasting glucose: a few times per week if self-monitoring.
Your healthcare professional may adjust this schedule based on medication, age, or health status. HOW TO READ TRENDS Instead of focusing on single numbers, look for patterns: Signs of improvement:
- Lower A1C.
- Lower fasting glucose.
- Fewer high postmeal spikes.
- Improved triglycerides and HDL.
- Reduced liver enzymes.
- Stable kidney function.
Signs that adjustments may be needed:
- Rising A1C or fasting glucose.
- Higher triglycerides.
- New abnormal liver tests.
- Changes in kidney function.
- Large day to day glucose swings.
DISCUSSING RESULTS WITH YOUR HEALTHCARE TEAM Prepare questions such as:
- What is my A1C trend?
- Are my kidneys and liver healthy?
- Do I need to change any medication?
- What habits are helping the most?
- What should I focus on next?
Bring:
- Your recent glucose readings if using a meter or CGM.
- Any symptoms or concerns.
- Any changes in lifestyle or stress.
KEY POINTS SUMMARISED
- Blood tests show how well glucose and organs are functioning.
- A1C provides a 3-month average; fasting and postmeal tests show daily patterns.
- Kidney, liver, and lipid tests detect silent problems early.
- Thyroid and vitamin tests identify issues that affect energy and glucose.
- Reading trends over time is more important than single results.
- Discussing results regularly with your healthcare team helps guide long term success.
These explanations help make blood test results meaningful and empowering rather than confusing or frightening.