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nurse helping man with diabetes


Diabetes is a life-long health condition caused by excess levels of glucose in the blood

Diabetes is a lifelong condition that causes a person's blood glucose level to become too high, due to a relative lack of, or increased resistance to insulin. Insulin facilitates the transport of glucose into the cells. In diabetes mellitus, because of a lack of insulin (type 1) or resistance to it (type 2), glucose cannot get into the cells of the body where it is used for fuel. Elevated blood glucose levels can lead to sight loss, amputation, kidney failure, stroke, and death. More than 500 people with diabetes die prematurely every week.

This resource has been developed with the RCN Professional Lead and the RCN Diabetes Forum alongside expert members and forum link nurses.

Whilst both type 1 and type 2 diabetes are characterised by having higher than normal blood glucose levels, the cause and development of the conditions are different. About 90% of people with diabetes have type 2, 8% have type 1 and about 2% have rarer types.

Diabetes mellitus is a significant global burden for health care. There are approximately 537 million people worldwide living with diabetes and, in the UK, around 6.3% of the adult population, aged between 20 – 79 have the condition (International Diabetes Federation (IDF) Atlas 2021). Across the UK there are over 3.8 million people with a diagnosis of diabetes mellitus and an estimated one million people who have the condition, but don’t know it (Diabetes UK, 2019 Facts and Stats). This represents approximately 9% of the UK population.

Type 1 diabetes

Type 1 diabetes is an autoimmune disease, which develops when the insulin-producing cells in the body are destroyed, and the body is unable to produce insulin. It is unclear why this happens, but the most likely reason is that the body has an abnormal reaction to the pancreatic beta cells which produce insulin and begins to destroy them. This could be triggered by an infection or virus but again this is not known for sure. It can develop at any age but usually appears before the age of 40, and especially in childhood. A person with type 1 diabetes will need to take insulin injections or use an insulin pump for life. They will also need to ensure that their blood glucose level stays balanced by eating a healthy diet, take regular physical activity and carry out regular blood glucose testing. 

Type 2 diabetes

Type 2 diabetes develops when the body can still produce some insulin but not enough for it to function properly, or when the cells in the body do not react properly to insulin. This is called insulin resistance. The treatment of type 2 diabetes centres on lifestyle management including a healthy diet, regular exercise and the person monitoring their blood glucose level. As the condition progresses over time, oral therapies are used.  There are several oral therapies for diabetes. Some help the body to use insulin more effectively whilst others increase the amount of insulin that the body produces. However, if these do not prove to be an effective control, then the person with diabetes may require insulin or other injectable therapies (RCN, 2019).

Type 2 diabetes is often associated with obesity and later life. However, it is also increasingly becoming more common in children, adolescents and young people of all ethnicities but is particularly prevalent in people of South Asian ethnicity. Type 2 diabetes is far more common than any other type.

Diabetes in pregnancy

Approximately 5% of all women giving birth in England and Wales have either pre-existing or gestational diabetes (GD), GD accounts for 87.5% of these cases (NICE, 2020) NICE NG3 Diabetes and pregnancy. Gestational diabetes arises usually during the second or third trimester. The hormones produced during pregnancy can make it difficult for the body to utilise insulin properly. Women affected by gestational diabetes do not have diabetes before pregnancy and after giving birth, blood glucose levels return to normal. However, women with a history of gestational diabetes are at a seven-fold increased risk of developing type 2 diabetes in later life and should be made aware of the signs of hyperglycaemia alongside appropriate monitoring.  In women with gestational diabetes, blood glucose usually returns to normal soon after birth but can remain elevated requiring on-going management. 

Rare types

Rarer forms of diabetes may include monogenetic diabetes, cystic fibrosis related diabetes, and diabetes caused by rare syndromes. Certain medications such as steroids and antipsychotics and surgery for hormonal imbalances could also lead to other types of diabetes.  

Typical symptoms of diabetes may include:

  • feeling very thirsty (polydipsia)
  • passing urine more often than usual (polyuria), particularly at night (nocturia)
  • feeling very tired
  • weight loss and loss of muscle bulk
  • losing weight without trying to
  • genital itching or thrush
  • cuts and wounds taking longer to heal
  • blurred vision.


A patient diagnosed with diabetes will need to take additional care of their health. They will need on-going advice and support about maintaining a healthy diet, keeping active and monitoring their condition. People with diabetes can live normal active and healthy lives. Small adjustments to their lifestyle can make significant improvements. Most diabetes management relies on a person 'self-managing' their condition, so motivation is a major consideration regarding effective treatment.

Emotional Well-being

The complexity and demands of diabetes impacts effective self-care; as such, the impact on psychological and emotional well-being can be profound. Providing the right emotional support should not be limited to people with diagnosable psychological disorders but should be an integral component of care for all people living with diabetes (Diabetes UK, 2019 - Diabetes UK Diabetes and emotional health resource)

Non-diabetic hyperglycaemia / Pre-diabetes

Non-diabetic hyperglycaemia (NDH – previously known as pre-diabetes, PHE 2015) is often used to describe people who have an elevated risk of developing diabetes, however, these are not recognised clinical terms. NDH occurs when blood glucose levels exceed normal levels but do not climb high enough to warrant a diagnosis of diabetes. This may also be referred to as borderline diabetes, Impaired Glucose Tolerance (IGT), Impaired Fasting Glycaemia (IFG) and Impaired Glucose regulation (IGR).

If NDH is undiagnosed and untreated the person will almost certainly develop type 2 diabetes. Approximately 11.4% of people are living with NDH. Many people often do not know that they have it until it is too late as there are sometimes no noticeable symptoms.

NDH is closely linked to obesity and other lifestyle choices and is putting an increasing burden on the health care system. People diagnosed with NDH can slow down or prevent the condition from developing into type 2 diabetes by making lifestyle changes.

The following are significant factors in the prevention of type 2 diabetes and should be discussed with each person:

  • healthy eating
  • keeping active
  • weight management
  • smoking cessation and alcohol consumption
  • emotional wellbeing.

Diagnosing diabetes – assessing risk

Diabetes UK supports the diagnostic criteria published by the World Health Organisation (WHO) in 2006: Definition and diagnosis of diabetes mellitus and intermediate hyperglycaemia and in 2017: Classification of diabetes mellitus (2019). Diabetes UK also welcomed the 2011 decision by the WHO to accept the use of HbA1c testing in diagnosing diabetes: Use of glycated haemoglobin in the diagnosis of diabetes mellitus.

For more information on diagnostic criteria for diabetes, see: Diabetes UK: Diagnostic criteria for diabetes

For information and interactive guidance to assess risk of type 2 diabetes see: Diabetes UK, Know your risk