Diabetes (AQA GCSE Biology): Revision Notes
Diabetes
What is diabetes?
Diabetes is a condition where the body cannot control blood glucose levels properly. This means blood sugar can become too high, which is dangerous for the body.
There are two main types of diabetes, and they have different causes and treatments.
Understanding the difference between Type 1 and Type 2 diabetes is crucial because they have completely different causes and require different treatment approaches.
Type 1 diabetes
Type 1 diabetes is an autoimmune condition where the body's own immune system mistakenly attacks healthy cells.
What causes type 1 diabetes:
- The body's immune system attacks and destroys special cells in the pancreas
- These pancreatic cells normally make insulin
- Without these cells, the pancreas cannot make enough insulin
- Insulin is the hormone that controls blood glucose levels
People with Type 1 diabetes cannot survive without insulin injections - their pancreas produces little to no insulin on its own.
Treatment:
- People with type 1 diabetes need insulin injections
- They must inject insulin regularly to control their blood sugar
- Diet alone cannot treat type 1 diabetes
When it happens:
- Type 1 diabetes often develops in childhood
- It can happen at any age but is more common in young people
Type 2 diabetes
Type 2 diabetes is characterised by insulin resistance, where the body's cells don't respond properly to insulin.
What causes type 2 diabetes:
- The liver and muscle cells stop responding to insulin properly
- The pancreas might not make enough insulin
- This means glucose builds up in the blood instead of entering cells
Unlike Type 1, Type 2 diabetes is often preventable through lifestyle changes and maintaining a healthy weight.
Treatment:
- A controlled diet with less sugar and carbohydrates
- Regular exercise to help the body use glucose
- Some people may need medication later
When it happens:
- Type 2 diabetes usually develops when people are over 30 years old
- It is linked to being overweight or obese
Body mass index (BMI)
BMI stands for body mass index. It measures whether someone has a healthy weight for their height.
BMI categories:
- Under 18.5 = underweight
- 18.5-25 = normal weight
- 25-30 = overweight
- Over 30 = obese
How to calculate BMI:
Worked Example: Calculating BMI
A person who weighs 66kg and is 1.73m tall:
Step 1: Apply the formula
Step 2: Calculate the height squared
Step 3: Divide mass by height squared
Result: This person has normal weight (BMI = 22).
Link between obesity and diabetes
There is a strong correlation between body weight and the risk of developing Type 2 diabetes.
Key facts:
- Being overweight or obese is a major risk factor for type 2 diabetes
- The higher someone's BMI, the greater their risk of developing type 2 diabetes
- This is especially true for people with BMI over 30 (obese)
- Women have a higher risk than men at the same BMI levels
Risk Alert: People with a BMI over 30 have a significantly increased risk of developing Type 2 diabetes compared to those with normal weight.
Why this happens:
- Extra body fat makes it harder for insulin to work properly
- This means the body cannot control blood glucose as well
Maintaining a healthy weight through proper diet and regular exercise is one of the most effective ways to prevent Type 2 diabetes.
Remember!
Key Points to Remember:
- Diabetes means the body cannot control blood glucose properly
- Type 1 = immune system destroys insulin-making cells, needs insulin injections, often starts in childhood
- Type 2 = cells don't respond to insulin properly, treated with diet and exercise, usually starts after 30
- BMI over 30 greatly increases the risk of type 2 diabetes
- Type 2 diabetes is preventable - maintaining a healthy weight helps prevent it