Information for the public

Terms explained

Autoimmune condition

A condition where your immune system (the body's defence against infection and disease) starts to attack healthy tissues and organs. In type 1 diabetes the healthy cells of the pancreas that normally make insulin are destroyed. A person who has type 1 diabetes may also have an increased risk of other autoimmune conditions.

Cardiovascular disease

A general term for disease of the heart and blood vessels. It is usually caused by a narrowing of the blood vessels so that blood cannot flow to the heart, brain, feet or other parts of the body properly. Heart disease and stroke are common forms of severe cardiovascular disease.

Continuous glucose monitoring

This includes real-time continuous glucose monitoring (rtCGM) and intermittent-scanning continuous blood glucose monitor (isCGM, also called 'flash'). Both types of continuous glucose monitor work with a sensor that you wear on your skin, and a display monitor or smartphone that shows your blood glucose level. rtCGM devices automatically send regular readings to the monitor or smartphone. You need to scan isCGM devices yourself.


A hormone that raises blood glucose levels. It can be given as an injection in emergencies to people with diabetes who have severe hypos.

HbA1c test

A blood test that reflects the average blood glucose level over the previous 2 to 3 months. The result is usually given in mmol/mol (it used to be given as a percentage). In people without diabetes, it is usually below 42 mmol/mol (or 6%).


A higher than normal level of glucose in the blood. Symptoms include feeling thirsty and hungry, and increased urination. If it is not treated, hyperglycaemia can be associated with diabetic ketoacidosis, which happens when the lack of insulin becomes severe. Over time, hyperglycaemia also increases the risk of eye, gum, nerve, kidney and cardiovascular disease.

Hypo (hypoglycaemia)

A lower than normal level of glucose in the blood – usually less than 3.5 mmol/litre. The symptoms of a hypo include feeling dizzy (or even losing consciousness), feeling tired, feeling hungry, shaking and sweating. It is important to recognise the warning signs of a hypo. A severe hypo is where the person with diabetes needs help from someone else to treat the hypo.

Insulin pump

A small device that is attached to the body and delivers a steady flow of short‑acting insulin through a tube and needle into the layer of fat just under the skin. It allows the person to manage their blood glucose levels by modifying the insulin dose.


Harmful ketones in the blood are produced when the body starts to use its fat stores to make energy. It normally only does this if the body has a severe lack of insulin, or during starvation or severe stress. High levels of ketones can lead to diabetic ketoacidosis.


A medicine (tablet) that lowers blood glucose levels in people with type 1 diabetes through improving the action of insulin. Metformin does not increase insulin levels. It can increase the risk of hypos when taken with insulin.


Another name for kidney disease. Type 1 diabetes can cause the small blood vessels in the kidneys to be damaged so that they stop working properly. The earliest sign is having a protein called albumin in the urine.


Damage or disease that affects the nerves. Type 1 diabetes can cause neuropathy as a result of damage to the small blood vessels that supply nerves. Because nerves affect all parts of the body, neuropathy can have a number of effects.

'Off-label' use

In the UK, medicines are licensed to show that they work well enough and are safe enough to be used for specific conditions and groups of people. Some medicines can also be helpful for conditions or people they do not have a licence for. This is called 'off‑label' use. Off‑label use might also mean the medicine is taken at a different dose or in a different way to the licence. There is more information about licensing medicines on the NHS website.


An eye condition where the retina (the seeing part of the eye) is damaged. Type 1 diabetes can cause the small blood vessels around the retina to become blocked or leaky, or grow in the wrong way, so that light cannot pass through properly.

Sick-day rules

This refers to what you should do if you are ill, because illness can affect your blood glucose levels. Your diabetes care team should give you information about this that covers things like checking your blood glucose more often, taking more insulin and checking for ketones.

Read more about making decisions about your care.

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