Type 2 diabetes develops as a result of the body becoming less responsive to the hormone insulin.

Explore causes

Type 2 diabetes is one of the most common long term health conditions in the world today. Whilst researchers have established a number of causal factors, many are still either yet to be confirmed or well understood.

Obesity is perhaps the most commonly cited causal factor but other factors can also play a part in the development of type 2 diabetes and offers explanation for why some people develop type 2 diabetes without being overweight.

How type 2 diabetes develops

Type 2 diabetes develops as a result of the body becoming less responsive to the hormone insulin. This lack of responsiveness to insulin is termed as ‘insulin resistance’.

As the effect of insulin resistance grows, the body attempts to compensate by producing more insulin in order to keep blood glucose levels under control. If insulin resistance keeps developing, the body will find it ever harder to keep control of blood sugar levels leading to type 2 diabetes.


A number of different genes have been shown to increase the risk of type 2 diabetes. To date, research has found several dozen different genes linked with a susceptibility to insulin resistance and type 2 diabetes.

Whilst genetics can predispose people to type 2 diabetes, the condition will generally require one or more environmental factors to develop.

Weight gain and visceral fat

There is a strong connection between a larger waist circumference and insulin resistance, with obesity widely cited as one of the strongest risk factors for type 2 diabetes. When populations with type 2 diabetes have been researched, an increase in waist circumference has been shown to be proportional to the severity of insulin resistance.

For many years researchers were not sure why some people that were overweight developed type 2 diabetes whilst others did not.

Research has since found that people that develop type 2 diabetes have a much higher tendency to have a buildup of fat within the abdominal cavity that surrounds key organs such as the liver, pancreas and digestive organs. This form of fat is known as visceral fat.

Diet and sedentary lifestyle

Diet has been shown to be a strong contributory factor in the pathogenesis of type 2 diabetes with animal studies showing that high calorie diets and little physical activity greatly increase the risk of developing type 2 diabetes.

Diet is still very much a hot area of type 2 diabetes research, however, as researchers look to discover whether particular areas of the diet are more responsible than others for the development of the condition.


A number of medications have been shown to increase or lead to the development of insulin resistance.

Medications shown to be associated with an increased risk of type 2 diabetes include:

  • Corticosteroids
  • Thiazide diuretics
  • Beta-blockers

The likelihood of developing type 2 diabetes may increase with dose strength and duration of medication usage.

Cases whereby medication has been shown to bring on diabetes may be referred to as ‘drug induced diabetes’.


Stress is the biological response to a situation, often a threat, which results in a hormonal response to increase alertness and ready the body for taking action. The hormonal response includes raising blood pressure and blood glucose levels.

If stress becomes a persistent state, this is termed chronic stress which can affect the body’s metabolism and can raise the risk of developing type 2 diabetes.

Other possible causes of type 2 diabetes

Significant associations have been drawn between type 2 diabetes and levels or air pollution and exposure to certain chemicals such as those found in makeup and common food packaging such as bottles and cans.

More research will be required, however, before these can be confirmed as definite causes.