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Type 2 diabetes – what's going on in your body?

If you have type 2 diabetes, your body gradually stops making enough insulin and becomes less able to use the insulin it does make effectively1. With too little insulin, your body cannot absorb glucose from the food you eat and your blood sugar levels rise and become harmful to your health2.

Understanding the connection between insulin, blood sugar and your average blood sugar levels over time – also known as HbA1c – is important for controlling type 2 diabetes3.

Why is HbA1c important?

HbA1c is a measure of your blood sugar levels over the last two to three months3. Your healthcare professional will perform a blood test to measure your HbA1c and use this to set a target blood sugar range for you.

If you have type 2 diabetes, every 1% drop in HbA1c reduces your risk of complications4. The HbA1c target ranges for people with prediabetes and type 2 diabetes are shown in this image5.

High and low blood sugar levels

While it is very important to stay within the target HbA1c range determined by your doctor, it is normal for your blood sugar to fluctuate throughout the day depending on many factors. However, it can be dangerous if your blood sugar levels go above or below the healthy range and are left untreated3.

What is high blood sugar?

High blood sugar, known as hyperglycaemia or 'hypers', damage your blood vessels. It can reduce the supply of oxygen and nutrient-rich blood to your body's organs and nerves and, over time, cause serious health complications6.

Controlling your high blood sugar levels may help you avoid complications like7:

  • Heart attack
  • Stroke 
  • Reduced eyesight or blindness
  • Kidney disease
  • Nerve problems
  • Blocked circulation in the feet
  • Gangrene leg amputations

What is low blood sugar?

Low blood sugar, known as hypoglycaemia or ‘hypos’, occurs when blood sugar levels fall below 3.9 mmol/L or 70 mg/dL5,8.

Low blood sugar levels can also impact your health8.

What are the signs of low blood sugar?

You may have already experienced low blood sugar without knowing it. People with diabetes who are on medication need to be aware of the signs and symptoms of low blood sugar. They may include8:

  • Shakiness or feeling weak
  • Sweating, chills and clamminess
  • Confusion
  • Headache
  • Rapid/fast heartbeat
  • Light-headedness or dizziness
  • Nervousness, anxiety or irritability
  • Blurred or impaired vision

Low blood sugar and its symptoms can be dangerous and you need to know what to do if they happen.

What causes low blood sugar?

You can experience low blood sugar for many reasons, including if you8,9:

  • do unplanned exercise
  • have missed or delayed a meal or snack
  • take too much insulin or insulin secretagogue (insulin secretion inducers; sulfonyurea and glinides)
  • drink alcohol without food
  • experience stressful situations

Manage low blood sugar episodes

On average, studies show that people with type 2 diabetes on insulin treatment experience 23 low blood sugar episodes (mild or moderate) over a year10.

The effects of low blood sugar can be different for everyone and hypoglycaemia symptoms can range from mild to severe8,11.

Repeated hypoglycaemia can, over time, lead to 'hypo unawareness', where the warning symptoms of low blood sugar stop being felt, making it harder to identify and more difficult to manage12.

Download the Hypoglycaemia Profiler to help recognise and track your hypos.

It is important to speak with a doctor or a nurse if you are experiencing low blood sugar. In some cases, it is a good idea to drink a fruit juice or eat candies in order to get immediate relief, or eat sugar tablets if you have them under the recommendation of your doctor or nurse13. Your doctor can help you find the best option for you in case of hypoglycemia and may adjust the dose of your other diabetes medicines to reduce the risk of low blood sugar.


  1. Diabetes UK. Type 2 Diabetes. Available from: https://www.diabetes.org.uk/diabetes-the-basics/types-of-diabetes/type-2. Last accessed: March 2024.
  2. Centers for Disease Control and Prevention. Insulin Resistance and Diabetes. Available from: https://www.cdc.gov/diabetes/basics/insulin-resistance.html. Last accessed: March 2024.
  3. Centers for Disease Control and Prevention. All about your A1C. Available from: https://www.cdc.gov/diabetes/managing/managing-blood-sugar/a1c. Last accessed: March 2024.
  4. Lind M, Imberg H, Coleman RL, Nerman O, Holman RR. Historical HbA1c Values May Explain the Type 2 Diabetes Legacy Effect: UKPDS 88. Diabetes Care. Published online July 7, 2021. doi:10.2337/dc20-2439
  5. American Diabetes Association Professional Practice Committee. 6. Glycemic Goals and Hypoglycemia: Standards of Care in Diabetes-2024. Diabetes Care. 2024;47(Suppl 1):S111-S125. doi:10.2337/dc24-S006
  6. Centers for Disease Control and Prevention. The effects of diabetes on the brain. Available from: https://www.cdc.gov/diabetes/library/features/diabetes-and-your-brain.html. Last accessed: FMarch 2024.
  7. Mouri MI, Badireddy M. Hyperglycemia. [Updated 2023 Apr 24]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK430900/
  8. Diabetes.co.uk. Hypoglycemia (low blood glucose levels). Available from: https://www.diabetes.co.uk/Diabetes-and-Hypoglycaemia.html. Last accessed: March 2024.
  9. Diabetes.co.uk. Stress and blood glucose levels. Available from: https://www.diabetes.co.uk/stress-and-blood-glucose-levels. Last accessed: March 2024.
  10. Edridge CL, Dunkley AJ, Bodicoat DH, et al. Prevalence and Incidence of Hypoglycaemia in 532,542 People with Type 2 Diabetes on Oral Therapies and Insulin: A Systematic Review and Meta-Analysis of Population Based Studies. PLoS One. 2015;10(6):e0126427. Published 2015 Jun 10. doi:10.1371/journal.pone.0126427
  11. International Diabetes Federation. IDF Atlas 10th Edition, 2021. Available from: https://diabetesatlas.org/idfawp/resource-files/2021/07/IDF_Atlas_10th_Edition_2021.pdf. Last accessed: March 2024.
  12. Diabetes.co.uk. Hypo Unawareness. Available from: https://www.diabetes.co.uk/hypo-unawareness.html. Last accessed: March 2024.
  13. Diabetes.co.uk. How to treat a hypo. Available from: https://www.diabetes.co.uk/how-to/treat-a-hypo.html. Last accessed: March 2024.

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