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Type 2 Diabetes Mellitus (T2DM)

What is type 2 diabetes?

Type 2 Diabetes Melitus (T2DM), known more commonly as type 2 diabetes, is a condition in which the bodies’ ability to control the level of blood sugar is impaired. It tends to develop over-time and mostly occurs in people aged in their 50s but commonly affects those aged 20 – 70 years of age.

The level of sugar in a person’s blood is tightly regulated to make sure the body can undertake everyday functions and whilst avoiding the damaging effects of high blood sugar. The pancreas is an organ in the abdomen that produces the hormone insulin which circulates in the blood and lowers the blood sugar level.

In type 2 diabetes, the body becomes resistant to the effects of insulin and the pancreas’ ability to produce insulin in the quantity required is gradually impaired. The overall effect of this is that there is an inability to control blood sugar levels within a normal range. This leads to long-standing increase in blood sugar levels which increases the risk of developing cardiovascular disease and can directly damage the blood vessels and nerves, in particular, those supplying the kidneys and eyes. Insulin also allows the body to use the sugar in blood, without it there is reduced uptake of sugar intake the organs and muscles. 

In the normal body, insulin is released by pancreas and it is recognised by receptors on the target cell, which then carry out the relevant functions to reduce and control blood glucose. In type 1 diabetics, the pancreas are unable to produce insulin. In type 2 diabetics, the pancreas produce insulin but the cells do not respond properly to the insulin.

What causes type 2 diabetes mellitus?

The cause of type 2 diabetes is an interplay of genetic (susceptibility) factors with environmental (lifestyle) exposures. Type 2 diabetes is primarily caused by the development of resistance to insulin, which means more insulin is required to achieve the same level of blood sugar control. The pancreas produces less insulin with increasing age and increasing demands, which ultimately leads to lower levels of insulin being able to be produced by the body and hence leading to loss of the ability to control your blood sugar.

Resistance to insulin has been found to have strong genetic links and is very common within families affected. Type 2 diabetes is said to be polygenic, meaning a variety of genetic factors are involved. It is thought that the chances of becoming type 2 diabetic is up to 6 times greater if anyone in your immediate family also are diabetic and up to 4 times greater if you are of South Asian or Afro-Caribbean descendance. It also is associated with ageing, being overweight or obese (especially around the middle of your body, also known as central obesity). 

An overview of risk factors is included below:

  • Over 40
  • Overweight/obes
  • Immediate relative who is a diabetic
  • South Asian or Afro-Caribbean descendance
  • Smoking
  • Excessive alcohol consumption
In type 2 diabetes, the cells in the body develop resistance to insulin, meaning the pancreas have to release more insulin to achieve the same level of blood sugar control

How is Type 2 Diabetes diagnosed?

The diagnosis of type 2 diabetes is made on the grounds of a blood test indicating that the body is unable to control blood sugar levels within a normal range.

The first investigation undertaken in most people will be to test the level of blood glucose (sugar). This can be taken after a person has been instructed not to eat (fasting test) or in the form of a glucose tolerance which involves a blood test 2 hours after consuming a set amount of sugar in the form of a drink. Measuring a marker known as HbA1c can indicate the average level of blood glucose over 90 days and both helps in the diagnosis and monitoring of the condition. 

How common is type 2 diabetes?

Type 2 diabetes accounts for up to 90% of all causes of diabetes. In the UK, almost 5 million people have diabetes, with a further 14 million with an elevated risk of developing type 2 diabetes. The age at one is diagnosed with type 2 diabetes is dependent on many factors, however it tends to occur in people aged in their 50s. The number of people developing Type 2 diabetes is increasing across the world and it is thought to affect over 400 million people worldwide. There is significant geographical variation in the number of people suffering from type 2 diabetes, with the lowest incidence reported in African countries and the highest incidence in Western Pacific countries. 

An overview of results indicative of diabetes are included below:

1. HbA1c of 48 mmol/mol (6.5%) or more.

2. Fasting plasma glucose level of 7.0 mmol/L or more.

3. Random plasma glucose of 11.1 mmol/L or more in the presence of symptoms or signs of diabetes.

If one doesn’t suffer from any symptoms, then a repeat test to ensure the correct diagnosis is recommended. However, if someone suffers from increase urination or thirst, blurred vision, unexplained weight loss or tiredness, then a single test result can confirm the diagnosis.