What Causes Type 2 Diabetes?

Nature vs. nurture - what causes someone to develop type 2 diabetes?

Type 2 diabetes is a progressive condition, in which the body either doesn’t produce enough insulin, or it isn’t capable of using the insulin it produces to regulate glucose levels in the blood. If undetected or untreated, this insulin resistance ultimately results in hyperglycemia, the presence of dangerously high levels of glucose building up in the blood instead of being processed into cells in multiple areas of the body. These areas of the body can eventually become damaged, as their cells cannot function without being energized by the glucose.

What causes type 2 diabetes?

No one knows exactly what causes type 2 diabetes, but several factors can influence whether you will - or won’t, develop the condition.


Family history can play a role in the cause of type 2 diabetes. If you have a close relative who has type 2 diabetes, you are at increased risk of developing the condition as well. There may even be certain genetic mutations that predispose people to type 2 diabetes. However, this does not mean you will certainly become a type 2 diabetic; it just means you will be more vulnerable, in the face of other causal factors.

Lifestyle choices

While a genetic mutation may make you more susceptible to developing type 2 diabetes, the lifestyle choices you make may ultimately determine whether your “at risk” status is downgraded to “type 2 diabetic.” These include:

  • Being overweight: The more fatty tissue you have, the more resistant your cells become to insulin. And if your body primarily stores fat in your abdomen, your risk of type 2 diabetes is greater than if your body stores fat in your hips or thighs.
  • Not exercising: Physical activity has many benefits - it helps you control your weight, uses the glucose in your blood as energy and makes your cells more sensitive to insulin. Not exercising has the opposite effect.
  • Not sleeping: Studies show that insulin resistance can be increased by sleep deprivation, even one night's worth! As such, chronic poor sleep may be a causal factor in the development of type 2 diabetes.
  • Making unhealthy food choices: Your risk of type 2 diabetes is greater is you tend to fill your plates with high-fat foods or refined sugars, but avoid ingesting fiber (found in grains, vegetables, and fruits).
  • Residing in poor environmental conditions: Several classes of chemicals, when present in the environment, are known to increase insulin resistance - persistent organic pollutants (POPs). These can include dioxins, pesticides, plastics called “phthalates,” flame retardants in furniture and polluted air. A study found that people with high levels of POPs in their bodies were 37 times more likely to have diabetes than people with low or negligible levels of POPs in their bodies.

Who is more likely to develop type 2 diabetes?

You are more likely to develop type 2 diabetes if you:

  • Have a family history of diabetes
  • Are overweight - with a body mass index (BMI) of over 25
  • Are inactive
  • Are over 40 years old
  • Are of Aboriginal, Hispanic, Asian, South Asian, or South African descent
  • Experience stress or trauma
  • Have a high alcohol intake
  • Have high blood pressure
  • Have high cholesterol levels
  • Have IGT or impaired fasting glucose
  • Have Polycystic Ovarian Syndrome
  • Developed gestational diabetes while pregnant
  • Gave birth to a large baby (over 4 kg/9 lbs)