IB Biology SL

Revision Notes

2.3.5 Skills: Calculating BMI

Diabetes

Type 1 diabetes

  • Type 1 diabetes is a disorder in which the pancreas fails to produce sufficient insulin to control blood glucose levels
    • Scientists think this is a result of a person’s own immune system destroying the cells of the pancreas that make insulin during development
  • Type 1 diabetes is characterised by uncontrolled high blood glucose levels and is normally treated with insulin injections

Type 2 diabetes

  • In Type 2 diabetes the body cells no longer respond to insulin produced by the pancreas – the person still makes insulin but their cells are resistant to it and don’t respond as well as they should
  • This can also lead to uncontrolled high blood glucose levels
  • A carbohydrate-controlled diet and an exercise regime are common treatments for Type 2 diabetes

Comparing Type 1 & Type 2 diabetes

Comparing Type 1 & Type 2 diabete_1, downloadable IGCSE & GCSE Biology revision notes

Correlation between body mass and Type 2 diabetes

  • Obesity is a major risk factor for Type 2 diabetes – obese individuals have an increased risk of developing the condition compared to non-obese individuals
  • This is probably because a person who is obese is likely to consume a diet rich in carbohydrates which causes an over-production of insulin resulting in the development of insulin resistance

The body mass index

  • An individual is classified as obese if their BMI (body mass index) is greater than 30
  • BMI is worked out using the following formula:

BMI = mass (kg) ÷ height (m)2

  • An individual with a BMI over 30 has an increased risk of developing Type 2 diabetes

The waist-to-hip ratio

  • Where on the body excess fat is being stored also plays a role
  • Individuals with a lot of excess fat stored around the abdomen area have an increased risk of developing Type 2 diabetes
  • Calcuating a waist-to-hip ratio gives an indication of how much fat is being stored in this area
  • A ratio above 1.0 for men and 0.85 for women is associated with increased risk of developing Type 2 diabetes
  • The ratio can be calculated using the following formula:

Waist-to-hip ratio = waist circumference (cm) ÷ hip circumference (cm)

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