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 830 million people worldwide living with diabetes. It is estimated that more than 5.6 million people in the UK are living with diabetes, which is an all-time high.

Diabetes UK (2024) data shows that 4.4 million people in the UK live with diabetes. Additionally, 1.2 million people could be living with type 2 diabetes who are yet to be diagnosed. These registration figures for 2022-23 are up by 167,822 from 2021-22.

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

Gestational diabetes affects at least 4 to 5 in 100 women during pregnancy, or 1 in 20 pregnancies in the UK.

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:

• Monogenic types of diabetes such as Maturity Onset Diabetes of the Young (MODY)
• Latent Autoimmune Diabetes in Adults (LADA)
• Type 3c – usually occurs from damage to the pancreas
• Steroid- induced diabetes
• Cystic fibrosis diabetes. 

Lifestyle

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. An estimated over 3.2 million people are at an increased risk of type 2 diabetes in the UK based on blood sugar levels. 

It is also estimated that 1.2 million people are currently living with type 2 diabetes but are yet to be diagnosed. 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

You can identify those who may be at risk of developing diabetes through specific tools such as the Know your risk tool.

For cases where you suspect a diagnosis of type 2 diabetes if an adult presents with persistent hyperglycaemia that may be accompanied by clinical features, you need to undertake some testing. 

These tests include measurement of:

• HbA1c (glycated haemoglobin) of 48 mmol/mol (6.5%) or more (will need two tests to confirm diagnosis if asymptomatic, if symptomatic then can use one test reading to confirm diagnosis) 
• Fasting plasma glucose level of 7.0 mmol/L or more.
• Random plasma glucose of 11.1 mmol/L or more in the presence of symptoms or signs of diabetes.

Useful resources

• Diabetes UK: Diagnostic criteria for diabetes.
• Diabetes UK: Know your risk.
• NICE (2024): How should I diagnose type 1 diabetes in an adult? For individuals with suspected type 1 diabetes, with acute symptoms of thirst, excessive urination, nausea, vomiting, weight loss and/or drowsiness, emergency review is required for appropriate management.
• NICE (2024): When should I suspect type 2 diabetes in an adult?