Types of diabetes
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Types of diabetes
This section looks at the different types of diabetes and how it can affect different age groups and stages in life.
Type 1
In type 1 diabetes the person is no longer able to produce any insulin at all. This is because all the cells in the pancreas that produce insulin have been destroyed. These cells are called pancreatic beta-cells and are destroyed by an autoimmune process. This means that the body’s immune system attacks and destroys parts of its own tissues. In the case of type 1 diabetes, the body’s immune system destroys all the pancreatic beta-cells resulting in the complete loss of ability to produce insulin.
A person with type 1 diabetes does not produce any insulin. This means they must inject insulin for the rest of their lives.
Insulin is essential to life. This means their insulin injections should NEVER be discontinued.
Stopping insulin injections in type 1 diabetes leads to a condition called diabetic ketoacidosis which is a life-threatening emergency.
What causes type 1 diabetes?
It is likely that the cause of type 1 diabetes is a combination of two factors. Firstly, some genetic variations which make the person susceptible to type 1 diabetes then something in their environment which triggers the autoimmune response. This is called an environmental trigger and an example might be catching a virus.
The most common age for this to happen is between 10 and 14 years old. It is usually diagnosed after a short period of passing lots of urine, thirst, tiredness and weight loss.
It is estimated that 400,000 people in the UK have type 1 diabetes (Diabetes UK, 2019).
This diagram is explained in this video produced by the charity Diabetes UK. See: What is Type 1 diabetes?
How is type 1 diabetes managed?
Good glycaemic control in type 1 diabetes can reduce long-term complications by up to 76% as shown in the seminal Diabetes Control and Complications Trial.
People with type 1 diabetes usually take four or five insulin injections per day. Some people with type 1 diabetes use an insulin pump. Their insulin doses must be adjusted around variables such as diet and exercise. People living with type 1 diabetes are taught to adjust their insulin on a structured education program. They are also taught carbohydrate counting.
Testing blood glucose is essential for adjusting insulin doses and avoiding hyperglycaemia and hypoglycaemia. NICE recommends testing between four and ten times per day for most people with type 1 diabetes. Some people with type 1 diabetes will wear a glucose monitoring sensor.
People living with type 1 diabetes also need to check their ketone levels sometimes. This is because ketones can be a sign of serious illness.
People with type 1 diabetes should be cared for by a specialist multidisciplinary team usually in secondary care. Self-management of type 1 diabetes is complex and demanding, and the person living with type 1 diabetes usually knows more about this than the non-specialist health care professional. For this reason, if they are able to, people with type 1 diabetes should manage their own insulin doses during a hospital admission.
Further resources
- NICE guideline (updated 2021) Type 1 diabetes in adults: diagnosis and management. This guideline covers care and treatment for adults (aged 18 and over) with type 1 diabetes. It includes advice on diagnosis, education and support, blood glucose management, cardiovascular risk, and identifying and managing long-term complications. In July 2021, NICE reviewed the evidence and updated the recommendations on long-acting insulin therapy.
Type 2
What causes type 2 diabetes?
Type 2 diabetes develops when the body can still produce some insulin but not enough for energy from glucose to be utilised properly, or when the cells in the body do not react properly to insulin. This is called insulin resistance.
How is type 2 diabetes managed?
The treatment of type 2 diabetes centres on lifestyle management including a healthy diet, regular exercise and the person monitoring their blood glucose level. The condition may progress over time and a number of oral glucose therapies are also used, with or without additional insulin injections and Incretin mimetics / GLP-1 analogues. Some medications help the body to use insulin more effectively whilst others increase the amount of insulin that the body produces.
Type 2 diabetes is often associated with obesity, and is also increasingly becoming more common in children, adolescents and young people of all ethnicities. Type 2 diabetes is far more common than type 1 diabetes - around 90% of all adults in the UK with diabetes have type 2 diabetes.
Type 2 diabetes risk factors include:
- carrying too much excess body fat – especially central body fat
- having high blood pressure or cholesterol
- genetics: having a close family member with type 2 diabetes (mother, father, brother or sister)
- having previously had gestational diabetes
- drugs such as steroids and anti-depressants
- ethnicity: common in Asian and Afro-Caribbean.
Further resources
Non-diabetic hyperglycaemia
Non-diabetic hyperglycaemia (NDH) is a recognised condition and a growing problem across the globe. It is closely linked to obesity and is putting an increasing burden on health care systems.
NDH is defined as an HbA1c of 42-47 mmol/ml or fasting plasma glucose of between 5.5-6.9 mmol/l in the last 12 months.
People with NDH are at increased risk of developing type 2 diabetes. They are also at risk of other cardiovascular conditions. 1.3 million people in England are recorded as having NDH (NHS Digital (2019) Diabetes Prevention Programme, 2017-18 Diagnoses and Demographics).
Many people often do not know that they have NDH or indeed, may not be diagnosed with type 2 diabetes until complications develop. People may live with type 2 diabetes for up to 10 years before noticing symptoms. It is estimated that a third of adults in England may have NDH (Diabetes UK. Prediabetes).
NDH occurs when blood glucose levels exceed normal levels but do not climb high enough to warrant a diagnosis of diabetes. It can be known as Impaired Glucose Tolerance (IGT) and Impaired Fasting Glycaemia (IFG).
NDH may sometimes be referred to as pre-diabetes – some healthcare professionals avoid this term as it is indicative of an inevitable progression to diabetes, which, with intervention may be avoided.
Today’s research builds on previous analysis, which found that improvement in lifestyle and diet resulted in a 7% reduction in the number of new diagnoses of Type 2 diabetes in England between 2018 and 2019, with around 18,000 people saved the consequences of the condition.
Impaired Glucose Tolerance
The patient's blood glucose level is raised beyond the normal range, but not to the diagnostic level of diabetes. Between 25% and 75% of people with IGT will develop diabetes within 10 years.
Impaired Fasting Glycaemia
The fasting blood glucose level is consistently elevated above what is considered normal, but not enough to be diagnosed as diabetes. It can progress into type 2 if lifestyle changes are not made. Information on the diagnostic ranges for IGT and IFG can be found in the diagnosis and screening section of this resource.
If your patient has NDH
If NDH is left untreated it will quickly develop into type 2 diabetes, usually in less than ten years. The average time that patients with IFG develop type 2 diabetes has been estimated to be less than 3 years (source: Progression From Newly Acquired Impaired Fasting Glucose to Type 2 Diabetes. Gregory A. Nichols, PHD1, Teresa A. Hillier, MD, MS1 and Jonathan B. Brown, PHD, MPP1).
The 2002 Diabetes Prevention Programme study showed that patients with pre-diabetes can prevent it developing into type 2 diabetes by making changes in their diet and increasing their physical activity, realising a 58% reduction in the incidence rate of diabetes. Working with your patient, you can support them in their lifestyle change and encourage them to be involved in the management of their condition.
Patients with NDH have the opportunity to change their condition and early supportive action can slow down or even stop the development of type 2 diabetes.
Diabetes and pregnancy
This section of the resource aims to give a summary of the issues caused by diabetes in pregnancy. It is written for non-specialist registered and unregistered nursing and midwifery practitioners. It is designed to promote the health of women with diabetes and their babies.
This section does not replace the need for registered practitioners to be familiar with their local protocols and pathways.
All registered practitioners should be aware of the national guidelines which underpin local protocols. Some of these are signposted below in the resources section.
Pregnancy and diabetes
Women with diabetes make up 5% of pregnancies in England and Wales. This is around 35,000 pregnancies per year (Diabetes UK, 2019).
Diabetes has a profound effect on the risks of pregnancy to the foetus and the mother. This in turn affects the care women with diabetes or a history of gestational diabetes need.
The challenge for health care professionals is to provide safe, competent care to a relatively rare but very high risk pregnancy group. Any woman with diabetes who is already pregnant should be referred to the specialist diabetes team immediately.
There are various types of diabetes affecting pregnancy:

*figures for England and Wales (Diabetes UK, 2019)
What are the risks of pregnancy in diabetes?
The complications of diabetes in pregnancy can be truly devastating. By planning pregnancy in diabetes and following effective care pathways from conception to delivery and beyond we have the opportunity to help women and babies avoid them.
It is helpful to understand the reasons why pregnancies in diabetes are high risk. Understanding this gives insight into the challenges women with diabetes experience during pregnancy. It also shows how important it is that the specialist diabetes team is involved in individual care planning as early as possible. Understanding the risks of pregnancy in diabetes also helps understand why planning the pregnancy is so important.
These risks are explained in more detail below:
Hypoglycaemia becomes more likely as blood sugar management is tightened using insulin. To bring their HbA1c down to a target of 48mmol/mol, women aim for a blood glucose below 7mmol/l before meals when planning for, and during pregnancy. Many areas now have funding for continuous glucose monitoring during pregnancy for women with type 1 diabetes to help avoid low blood glucose. This funding does not cover preconception or other types of diabetes. This means it is important that health care professionals are able to recognise the signs of hypoglycaemia and to help the woman recognise and treat these. Women using insulin must also be aware of DVLA rules for diabetes and driving.
Congenital abnormalities are more common if blood glucose is raised at conception and during the first trimester.
Birth injuries to mother and baby and macrosomia. Birth injuries are more likely in diabetes due to macrosomia. Macrosomia refers to abnormally large babies. This is due to the baby having excess nutrition during later gestation and is associated with raised blood glucose in the second and third trimesters. Large babies are more likely to suffer injuries and other complications during delivery.
Worsening diabetic retinopathy occurs in pregnancy due to the effects of tightening blood glucose control and the stresses of pregnancy on the blood vessels of the back of the eye. Retinal screening and stabilisation of retinopathy before trying to conceive are important. (Lo Wang and Shah 2016)
Pre-eclampsia occurs between 20 weeks of pregnancy and 6 weeks post-delivery. It is likely to be caused by inadequate blood supply to the placenta. The placenta keeps the foetus healthy by supplying nutrients and oxygen and removing waste products. Symptoms include high blood pressure, protein in the mother’s urine, headaches, visual disturbances and oedema to the face, hands and feet. Early detection and monitoring are important to prevent more serious complications including reduced foetal growth and maternal fitting, CVA and clotting disorders.
Miscarriage, still birth, neonatal death and birth before 37 weeks are all more common if diabetes is poorly controlled during the second and third trimesters. A miscarriage is when a baby dies before 24 weeks gestation and after this it is called a still birth. A neonatal death is when a baby dies within four weeks of being born. A baby born before 37 weeks gestation is considered to be premature and the earlier the birth the higher the risk to the baby of health problems (Tommys.org).
Neonatal hypoglycaemia is more common in poorly controlled diabetes during later pregnancy. If the blood supplied to the foetus through the placenta contains raised glucose then the foetus will produce more insulin. The baby will continue to produce more insulin after delivery and this can cause neonatal hypoglycaemia. This can potentially cause neonatal death and damage a baby’s neurological development (Lo Wang and Shah 2016).
How can nursing professionals support women with diabetes to plan pregnancies?
Pregnancy in diabetes should always be planned. This allows the multidisciplinary team to protect the mother and her baby from complications during pregnancy, delivery and beyond. Whilst all risk cannot be removed, planning a pregnancy allows the mother and baby’s health to be protected before trying to conceive and so reduces these risks.
Pre-conception counselling should be a routine part of diabetes care for all women of childbearing age. They should all be advised to use contraception according to their preference and to approach their health care team before stopping contraception.
Preconception care for diabetes includes:
- reducing the risk of congenital abnormalities and miscarriage
- screening the mother for complications of diabetes to manage them during the pregnancy
- managing blood glucose to a target HbA1c of 48 mmol/mol. One barrier to this is that hypoglycaemia becomes harder to avoid as blood glucose levels are reduced
- finding alternatives to medications known to be, or suspected of being harmful to the foetus
- and preparing the mother for the time, effort and lifestyle adjustments required for pregnancy and diabetes.
The risks of pregnancy in diabetes to the woman and her baby need to be discussed sensitively without scaring the woman. It should emphasise that her care before, during and after pregnancy is designed to reduce these risks and is based on the latest research. It is important that the woman with diabetes and her partner understand this so that they are motivated to manage the demands of diabetes treatment during pregnancy. Most antenatal clinics will see women with diabetes at least every fortnight. The time, effort and lifestyle adjustments required for pregnancy with diabetes are significant.
The woman should be referred to the specialist diabetes team for care planning and education according to the local pathway. Women often need specialist diabetes support to achieve their glucose targets before conception. They should be referred for structured education if they have not already had this opportunity.
It is important that the woman understands she should not stop using contraception until this is agreed with her health care team. She also should not tighten her glucose control rapidly until significant retinopathy has been excluded.
Blood and urine tests should be organised. These will include:
- HbA1c (to assess current glycaemic control)
- U+Es and urinary ACR (to assess for diabetic nephropathy).
It is also important to find out if the woman has had retinal screening in the last six months. If not, this should be booked. This allows significant retinopathy to be stabilised with laser therapy to reduce the risk of damage during pregnancy. She should not tighten her glucose control rapidly until this is done.
The woman will need a medication review before conception. This will include:
- review of her medications for diabetes, hypertension, dyslipidaemia and other comorbidities. Alternatives must be prescribed for medications known to be, or suspected of being, harmful to the foetus. For diabetes this effectively means optimising blood glucose on diet, metformin and insulin
- as in all pregnancies, Folic Acid 5mg OD should be started prior to trying to conceive. This is to reduce the risk of neural tube defects which can affect a baby’s brain and spinal cord or spine. This is a higher dose of Folic Acid than is used in pregnancies without diabetes.
Women with diabetes will also benefit from dietary education before conception and support to lose weight if their BMI is >27. In women who do not have diabetes, the risk of gestational diabetes increases if her BMI is above 30kg/m2. Thus losing weight before conceiving can reduce her risk of gestational diabetes.
To bring their HbA1c down to 48mmol/mol women aim for a target blood glucose of below seven before meals. This tight control increases the likelihood of episodes of hypoglycaemia. Many areas now have funding for continuous glucose monitoring during pregnancy for women with type 1 diabetes to help avoid low blood glucose. This funding does not cover the period before conception. Thus, it is important that health care professionals are able to recognise the signs of low blood glucose and to help the woman recognise and treat these. Women must also be aware of DVLA rules for diabetes and driving.
Further resources
- National Institute for Health and Care Excellence (NICE) (2015) Diabetes in pregnancy: management from preconception to the postnatal period
- Joint British Diabetes Societies for Inpatient Care (JBDS-IP) (2017) Management of glycaemic control in pregnant women with diabetes on obstetric wards and delivery units (PDF)
- Diabetes Technology Network UK (DTNUK) (2020) Best Practice Guide: Using diabetes technology in pregnancy (PDF)
- Royal College of Obstetricians and Gynaecologists. Gestational diabetes
- Low Wang, C., and Shah, A. (2016) Medical management of type 1 diabetes. Virginia: American Diabetes Association.
Children and diabetes
This section provides a brief overview of diabetes in childhood.
The nursing care of people under the age of 18 is beyond the scope of this resource which is for the care of diabetes in adults. Resources which may be useful to those working with diabetes in children are provided at the end of this section.
Over 3000 children in the UK are diagnosed with diabetes each year meaning that two in every 1000 children aged 18 and younger have diabetes.
- 95% of children have type 1
- 5% of children with diabetes have type 2 diabetes, cystic fibrosis related diabetes or monogenic diabetes (see table below) (NPDA, 2020).
The management of diabetes in children usually takes place in hospitals and is led by the paediatric diabetes multidisciplinary team.
Diagnosis of any type of diabetes in childhood is traumatic and living with diabetes in childhood is challenging. It affects the whole family as well as the child’s schooling and leisure activities. Adolescence can be a particularly challenging time when the young person struggles to come to terms with their diabetes. They begin to manage their own diabetes as they begin to take over from their parents. Regular contact with the diabetes team is important, as is maintaining a good, non-judgemental relationship with the young person.
Most services run a joint paediatric and adult clinic between the ages of 16 and 19. They support the young person as they begin to manage their diabetes independently whilst often sitting exams and looking for employment or further education places. Many services provide a Young Adult Diabetes Service to provide extra support up to the age of 25.
Further resources
Rare forms of diabetes
In addition to type 1, type 2 and gestational diabetes there are other types of diabetes, which are just as important to recognise.
Rare types of diabetes account for approximately 2% of people who have diabetes. These include different types of monogenic diabetes, secondary diabetes and diabetes caused by rare syndromes. Certain medications such as steroids and antipsychotics medications could lead to other types of diabetes, as well as having pancreatic surgery.
A misdiagnosis can lead to delays in getting the right treatment. Ongoing health care professional education and research are crucial to ensure better diagnosis and treatments for all types of diabetes.
Rarer types of diabetes
Type 3c diabetes
Type 3c diabetes is a type of diabetes that develops when the disease and/or surgery causes damage to the pancreas. This could be due to pancreatic cancer, pancreatitis, cystic fibrosis or haemochromatosis. Type 3c diabetes can also happen when part or all of the pancreas is removed because of other damage.
Steroid-induced diabetes
Some people who require steroids to treat other conditions can develop diabetes. This is known as steroid-induced diabetes, and is often more common in people who are at higher risk of type 2 diabetes.
Latent autoimmune diabetes in adults (LADA)
LADA is a type of diabetes which seems to overlap type 1 and type 2 diabetes. Some parts of it are more like type 1, and other parts are more like type 2. That's why it is sometimes called type 1.5 diabetes or type 1 ½ diabetes.
It’s not currently defined as a separate type of diabetes as more research is needed to help identify exactly what makes it different from type 1 and type 2 diabetes.
Monogenic diabetes (MODY)
MODY is a rare form of diabetes which is different from both type 1 and type 2 diabetes and it is characterised by strong family history of diabetes. MODY is caused by a mutation (or change) in a single gene. If a parent has this gene mutation, any child they have has a 50% chance of inheriting it from them. If a child does inherit the mutation, they will generally go on to develop MODY before they’re 25, whatever their weight, lifestyle, ethnic group etc.
Neonatal diabetes
Neonatal diabetes is a form of diabetes that is diagnosed under the age of six months. It’s a different type of diabetes to type 1 diabetes as it’s not an autoimmune condition (where the body has destroyed its insulin producing beta (β) cells) but caused by the single gene mutation (where the insulin producing β cells are switched off due to change in gene).
Wolfram Syndrome
Wolfram Syndrome is a rare genetic disorder which is also known as DIDMOAD syndrome after its four most common features (Diabetes Insipidus, Diabetes Mellitus, Optic Atrophy and Deafness).
Alström Syndrome
Alström Syndrome is a rare genetically inherited syndrome which has several common features including diabetes.
Cystic fibrosis diabetes
Cystic fibrosis diabetes is the most common type of diabetes in people with cystic fibrosis. Although it has features of both type 1 and type 2, it is a different condition.
Further resources
- Diabetes UK. Other types of diabetes
- DiabetesGenes. This website provides information for patients and professionals on research and clinical care in genetic types of diabetes.