A to Z glossary of insulin pump and diabetes terms

Active insulin

Also called insulin on board

Active insulin is the insulin from earlier doses that is still working in the body. Pump bolus calculators take it into account when working out a correction dose, which helps stop doses stacking on top of each other.⁶¹⁴ See also bolus calculator, correction dose, duration of insulin action.

Alarm

Also called an alert

An alarm is a warning signal from a pump or glucose monitor that something needs attention. The NHS says most continuous glucose monitors have optional alarms for glucose going too low or too high. See alarms and fail-safes for how pump alerts fit together.⁵⁶ See also continuous glucose monitoring, occlusion.

Analogue insulin

Analogue insulins are versions of human insulin whose structure has been modified to change how fast they act or how long they last. NICE says adults with type 1 diabetes should be offered rapid-acting analogues before meals.¹⁰¹⁸ See also rapid-acting insulin, insulin.

Automated insulin delivery

Also called AID

Automated insulin delivery is a system in which an insulin pump adjusts insulin by itself using readings from a glucose sensor. Diabetes UK treats it as another name for closed loop. ISPAD lists three parts: a pump, a CGM sensor and an algorithm.⁸¹⁴ See also closed loop, hybrid closed loop, continuous glucose monitoring.

Basal insulin

Also called background insulin

Basal insulin is the steady, background insulin that works across the day and night. On injections it is a long-acting insulin taken once or twice a day. A pump does the same job with small amounts of rapid-acting insulin, so no long-acting insulin is needed.³¹ See also basal rate, bolus, pump therapy.

Basal rate

The basal rate is the programmed pace at which a pump releases small amounts of insulin all the time. Diabetes UK says it is usually set in blocks of time with the healthcare team and can be changed, for example with activity. See how an insulin pump works.⁶ See also basal insulin, temporary basal rate, dawn phenomenon.

Blood glucose

Also called blood sugar

Blood glucose is the sugar in the blood, which the body uses for energy. People with type 1 diabetes learn to check it regularly and adjust their insulin, as agreed with their diabetes team, using a finger-prick meter or a sensor.¹² See also finger-prick test, mmol/L, HbA1c.

Blood ketones

Includes ketone testing

Ketones are harmful substances that build up when the body lacks insulin. They can be measured with a ketone meter on a drop of blood. The NHS says to test when glucose is high or when ill. See sick days with a pump.¹¹¹⁰ See also diabetic ketoacidosis, sick day rules, hyperglycaemia.

Bolus

A bolus is an extra dose of rapid-acting insulin taken to cover food or drink, or to bring down a high glucose level. On a pump, the user tells the device which bolus dose to give. See carbohydrate counting and boluses.¹⁶ See also bolus calculator, correction dose, extended bolus.

Bolus calculator

Also called bolus wizard

A bolus calculator is a pump feature that suggests a bolus dose from the carbohydrate entered and the current glucose reading. Diabetes UK says most pumps have one. ISPAD adds that current calculators also allow for insulin on board.⁶¹⁴ See also active insulin, carbohydrate ratio, insulin sensitivity factor.

Calibration

Calibration means checking a glucose sensor against a blood glucose meter reading so that the sensor readings are accurate. The NIDDK says some sensors need a finger-stick test to calibrate them, and NICE lists whether, and how often, a device needs calibrating as a factor when choosing continuous glucose monitoring.^{15 8} See also Sensor.

Cannula

A cannula is a very thin plastic or metal tube placed just under the skin, through which a pump delivers insulin. Diabetes UK says it is changed every two or three days, each time in a different place. See infusion sets and site rotation.¹⁶ See also infusion set, site rotation, site change.

Carbohydrate

Carbohydrate is the part of food and drink, found in starchy and sugary foods, that raises blood glucose. Because insulin is matched to the carbohydrate eaten, it is counted in grams or in portions using labels, books or apps.¹⁵⁹ See also carbohydrate counting, carbohydrate ratio.

Carbohydrate counting

Carbohydrate counting means working out the carbohydrate in what you eat and drink so that insulin can be matched to it. NICE says adults with type 1 diabetes should be offered carbohydrate-counting training as part of structured education.²¹⁰ See also DAFNE, carbohydrate ratio, bolus.

Carbohydrate ratio

Also called insulin-to-carbohydrate ratio

The insulin-to-carbohydrate ratio shows how many units of insulin are taken for a set amount of carbohydrate, or how many grams one unit covers. Diabetes UK says it varies from person to person and is worked out with the healthcare team.¹⁵¹⁶ See also bolus calculator, unit of insulin, insulin sensitivity factor.

Cartridge

Also called reservoir

The cartridge, or reservoir, is the container in a pump that holds the insulin. It needs refilling or replacing as it runs low. Diabetes UK notes that heat can damage insulin in the reservoir, so pumps need protecting from high temperatures.⁶⁸ See also infusion set, priming, tubing.

Closed loop

A closed loop is a system in which an insulin pump and a continuous glucose monitor "talk to each other" through a computer programme. The programme can sit on a phone, inside the pump or on a separate device, and it adjusts insulin automatically.⁸ See also hybrid closed loop, automated insulin delivery, DIY closed loop.

Continuous glucose monitoring

Also called CGM

Continuous glucose monitoring uses a small sensor worn on the skin to measure glucose in the fluid beneath it, sending readings to a reader, phone or pump every few minutes. The NHS says occasional finger-prick checks are still needed.⁵ See also flash glucose monitoring, sensor, finger-prick test.

Correction dose

A correction dose is extra rapid-acting insulin taken to bring a high glucose level down. Diabetes UK says a pump's bolus calculator works it out from the glucose reading and the insulin still on board. NHS Tayside calls the underlying setting the correction factor.⁶¹⁶ See also bolus, active insulin, insulin sensitivity factor.

DAFNE

Short for Dose Adjustment For Normal Eating

DAFNE is a structured education course for adults with type 1 diabetes, aimed at people aged 17 and over. It aims to help people live as normally as possible while keeping glucose within healthy targets. NICE names it as an example of a programme to offer.¹²¹⁰ See also carbohydrate counting, multiple daily injections, type 1 diabetes.

Dawn phenomenon

The dawn phenomenon is a rise in blood glucose in the early hours of the morning, when hormones signal the liver to release more glucose. The American Diabetes Association says about half of people with type 1 or type 2 diabetes experience it, and that a pump can be programmed to give more insulin then.¹³ See also basal rate, hyperglycaemia.

Diabetes specialist nurse

A diabetes specialist nurse is a nurse with expertise in diabetes who forms part of the diabetes care team. Diabetes UK describes the paediatric version as usually the first point of contact, giving advice and support between appointments.¹² See also paediatric diabetes team.

Diabetic ketoacidosis

Also called DKA

Diabetic ketoacidosis is a serious, life-threatening condition in which a lack of insulin lets ketones build up in the blood. It needs urgent hospital treatment. Diabetes UK says it can develop very quickly if a pump stops delivering insulin, because pumps use only fast-acting insulin.¹¹⁶ See also blood ketones, sick day rules, occlusion.

DIY closed loop

Also called open artificial pancreas system

A DIY closed loop is a home-built system in which people use algorithms they have created to let a pump talk to a glucose monitor. Diabetes UK says these systems are unregulated, are not available through the NHS, and that it cannot recommend them.⁸ See also closed loop, hybrid closed loop, MHRA.

Duration of insulin action

Duration of insulin action is how long a dose of insulin keeps working in the body. It matters for pump users because bolus calculators allow for the insulin that is still active from earlier doses.¹³¹⁴ See also active insulin, rapid-acting insulin, bolus calculator.

Extended bolus

Also called square bolus

An extended bolus delivers insulin slowly over a set period instead of all at once. ISPAD notes it can suit high-fat meals, where the glucose rise is delayed, and that a mix of immediate and extended delivery is called a combo or dual wave bolus.¹⁴ See also bolus, pre-bolus.

Finger-prick test

A finger-prick test checks blood glucose using a drop of blood, taken with a lancet and read by a meter. The NHS says people using CGM still need occasional finger-prick checks, particularly when driving or having a hypo.¹⁵ See also blood glucose, continuous glucose monitoring.

Flash glucose monitoring

Also called intermittently scanned CGM

Flash glucose monitoring uses a small sensor worn under the skin that stores glucose readings continuously. You scan it with a reader or phone whenever you want to see them. NICE uses the term intermittently scanned continuous glucose monitoring.¹¹⁰ See also continuous glucose monitoring, sensor.

Glucagon

Glucagon is a medicine given by injection to treat a severe hypo when someone is unconscious. The NHS says to give it straight away if one is available and you know how to use it, and to call 999 if not, or if there is no recovery within 10 minutes.⁷¹⁰ See also hypoglycaemia, impaired awareness of hypoglycaemia.

Glucose target

A glucose target is the level or range a person aims to keep their glucose within. The NHS says the care plan covers what your targets are. ISPAD notes that automated systems set a target as a single value or as a range.²¹⁴ See also time in range, HbA1c, hybrid closed loop.

HbA1c

Also written A1C

HbA1c is a blood test showing average blood glucose over the last 2 to 3 months, so it gives a longer-term picture than a single reading. The NHS says people with type 1 diabetes have it reviewed regularly.²¹³ See also time in range, mmol/L, blood glucose.

Hybrid closed loop

A hybrid closed loop links an insulin pump with a CGM so that a programme adjusts insulin automatically, while the user still enters carbohydrate before meals. NICE TA943 recommends it as an option for adults with an HbA1c of 58 mmol/mol (7.5%) or more or disabling hypoglycaemia, and for children, young people and pregnancy.⁴⁵ See also closed loop, automated insulin delivery, continuous glucose monitoring.

Hyperglycaemia

Also called a hyper

Hyperglycaemia means blood glucose that is too high. Symptoms include feeling very thirsty, peeing a lot and feeling tired. Diabetes UK says unexplained highs on a pump can come from problems with the infusion set, cannula or pump itself.⁹⁶ See also hypoglycaemia, blood ketones, diabetic ketoacidosis.

Hypoglycaemia

Also called a hypo

Hypoglycaemia is low blood glucose, which the NHS says is usually below 4 mmol/L. Symptoms include hunger, sweating, shaking and confusion, and a severe hypo can cause a seizure or unconsciousness. A person's own diabetes team gives individual advice on treatment.⁷ See also glucagon, impaired awareness of hypoglycaemia, low glucose suspend.

Impaired awareness of hypoglycaemia

Impaired awareness of hypoglycaemia means a person does not always notice the warning symptoms of a low glucose level. NICE says it is linked to a significantly increased risk of severe hypoglycaemia and lists an insulin pump and real-time CGM among ways to avoid hypos.¹⁰⁷ See also hypoglycaemia, pump therapy, continuous glucose monitoring.

Infusion set

An infusion set carries insulin from a tubed pump into the body, with tubing that connects to a cannula under the skin. Diabetes UK says a blocked or detached set can lead to high glucose and raise the risk of ketoacidosis. See infusion sets and site rotation.⁶¹⁴ See also cannula, tubing, site change, occlusion.

Insertion device

Also called inserter

An insertion device, or inserter, is a tool that places the cannula under the skin. One published study describes a spring mechanism that advances the needle and cannula to the right depth, after which the needle is withdrawn and the cannula stays in place.¹⁷⁶ See also cannula, infusion set, site change.

Insulin

Insulin is the hormone that keeps the level of glucose in the blood under control. In type 1 diabetes the body cannot produce it, so it has to be given, either by injection with a pen or through a pump.¹³ See also insulin pen, pump therapy, type 1 diabetes.

Insulin pen

An insulin pen is an easy-to-use injection device that helps you inject insulin safely and take the right dose. Some people use a pump instead, which gives small amounts of insulin throughout the day and night.¹³ See also multiple daily injections, pump therapy.

Insulin sensitivity factor

Also called correction factor

Insulin sensitivity factor, also called the correction factor, is the setting used to work out how much extra insulin to give when glucose is above target. NHS Tayside says it depends on the average total daily dose of insulin.¹⁶⁶ See also correction dose, carbohydrate ratio, total daily dose.

Lipohypertrophy

Lipohypertrophy is the formation of hard lumps of fatty tissue under the skin where insulin is given repeatedly. Diabetes UK says the lumps can stop insulin working properly, and ISPAD advises rotating infusion set placement. See infusion sets and site rotation.⁶¹⁴ See also site rotation, infusion set, cannula.

Low glucose suspend

Low glucose suspend is a pump feature that stops insulin delivery when sensor glucose reaches a programmed low threshold. ISPAD says the feature is optional and the pump works normally if it is switched off or sensor data are unavailable.¹⁴ See also predictive low glucose suspend, suspend, hypoglycaemia.

MHRA

Short for Medicines and Healthcare products Regulatory Agency

The MHRA is the UK regulator of medicines, medical devices and blood components for transfusion. It publishes guidance on regulating medical devices and runs the Yellow Card scheme, where anyone can report a problem with a medicine or medical device, which includes small devices such as insulin pumps.^{21 31} See also NICE.

mmol/L

Short for millimoles per litre

Millimoles per litre is the unit used in the UK to report how much glucose is in the blood. Diabetes UK, for example, gives time in range targets in this unit, while some countries, such as the United States, use mg/dL instead.^{23 32} See also Blood glucose.

Multiple daily injections

Also called MDI

Multiple daily injections means taking background (basal) insulin and mealtime (bolus) insulin as separate injections through the day. NICE advises this basal-bolus regimen as the injection option of choice for adults with type 1 diabetes, and says to consider an insulin pump for a child or young person if it is not appropriate.^{26 27} See also Pump therapy.

Neuropathy

Also called diabetic nerve damage

Diabetic neuropathy is damage to the nerves caused by diabetes. Diabetes UK explains that high blood sugar can harm the small blood vessels that supply the nerves, and the damage can affect the feet, organs and muscles. Read more in Diabetes and the nervous system.^{25 32}

NICE

Short for National Institute for Health and Care Excellence

NICE produces guidance for the NHS and the wider health and care system, including technology appraisals. Its guidance on insulin pump therapy (TA151) and hybrid closed loop systems (TA943) sets out which people it recommends them for, and the NHS in England must fund hybrid closed loop systems for the groups named.^{29 30} See also MHRA, Hybrid closed loop.

Occlusion

An occlusion is a blockage or kink in the path insulin takes from a pump to the body, such as the tubing or cannula, which slows or stops delivery. Pumps detect it by rising pressure and sound an alarm, but one review notes this can take hours, during which blood glucose may rise. See alarms and fail-safes.³⁵ See also Tubing, Cannula.

Paediatric diabetes team

A paediatric diabetes team is the multidisciplinary group of specialists who care for children and young people with diabetes. NICE says children with suspected type 1 diabetes should be referred to one on the same day, and that pump therapy should be started by a trained specialist team, which normally includes a diabetes specialist nurse and a dietitian.^{27 28} See also Diabetes specialist nurse.

Patch pump

A patch pump is an insulin pump that sits directly on the skin with no separate tubing and works with a handheld device. Diabetes UK says it is disposable, so the whole device is changed when it alerts you, and the cannula or patch pump needs changing every two or three days.²² See also Infusion set.

Pre-bolus

A pre-bolus is a mealtime dose of rapid-acting insulin taken some time before eating rather than at the start of the meal. A 2017 review in Diabetic Medicine found that taking it 15 to 20 minutes before a meal improved post-meal glucose control, while the diabetes team advises on timing. See carbohydrate counting and boluses.^{27 36} See also Bolus.

Predictive low glucose suspend

Predictive low glucose suspend is a feature of some sensor-linked pumps that pauses background insulin when glucose is predicted to fall to a set low level, then restarts it automatically once glucose recovers. A systematic review in children found it reduced time spent with low glucose compared with sensor-augmented pumps without it.^{37 38} See also Low glucose suspend.

Priming

Includes filling the cannula

Priming is the step of filling the pump tubing with insulin so that it is ready to deliver, and the cannula is filled once it has been inserted. An NHS trust leaflet and a UK clinical guide both list checking that the tubing is primed among the checks when glucose is unexpectedly high.^{34 40} See also Infusion set.

Pump therapy

Also called CSII, short for continuous subcutaneous insulin infusion

Pump therapy delivers insulin through a small device worn on the skin that gives tiny amounts day and night. NICE recommends it as an option for some adults and children with type 1 diabetes in set circumstances, and says it should be started by a trained specialist team. See how an insulin pump works.^{21 28} See also Basal rate, Bolus.

Rapid-acting insulin

Rapid-acting insulin is a mealtime insulin that acts quickly after it is given. NICE advises offering rapid-acting insulin analogues injected before meals to adults with type 1 diabetes, and tells children and young people on injections to inject rapid-acting analogues before eating.^{26 27} See also Analogue insulin, Bolus.

Sensor

Also called glucose sensor

A glucose sensor is a tiny device inserted under the skin, usually on the belly or arm and held in place with a sticky patch. According to the NIDDK it estimates the glucose in the fluid between your cells, which is close to blood glucose.³³ See also Continuous glucose monitoring, Transmitter.

Sick day rules

Sick day rules are guidance from a diabetes team on managing diabetes during illness, including adjusting insulin, checking blood glucose and ketones, and keeping up fluids. NICE says adults with type 1 diabetes should be given clear sick day rules, and Diabetes UK advises contacting your team if unsure. See sick days with a pump.^{24 26} See also Blood ketones.

Site change

A site change means replacing the cannula and infusion set, or the whole patch pump, and moving to a new place on the body. Diabetes UK says this is needed every two or three days, and a hospital leaflet describes the cannula as sitting in the tissue under the skin. See infusion sets and site rotation.^{22 40} See also Infusion set.

Site rotation

Site rotation means using a different place on the body each time insulin is delivered. Diabetes UK says to move to a different place at every change, because using one area too long can cause hard lumps that stop insulin working properly, as well as itching and rashes.^{22 32} See also Lipohypertrophy.

Subcutaneous

Subcutaneous means under the skin, in the layer of tissue just beneath it. The American Diabetes Association describes a subcutaneous injection as fluid put into that tissue, and NICE describes a pump as injecting insulin under the skin, which is why pump therapy is called continuous subcutaneous insulin infusion.^{29 32} See also Cannula.

Suspend

Suspend means pausing a pump's insulin delivery. Some systems do this automatically when sensor glucose is low or predicted to fall, then resume insulin once glucose recovers, and NICE refers to an insulin suspend function when listing factors for choosing glucose monitoring devices.^{26 37} See also Low glucose suspend.

Temporary basal rate

A temporary basal rate changes the background insulin a pump delivers for a fixed period, after which the pump returns to the usual rate. A UK best practice guide for clinicians notes that a change in basal insulin can take several hours to reach its full effect.³⁴ See also Basal rate.

Time in range

Time in range is the percentage of time that your blood sugar level stays within a target range. Diabetes UK says the target range is decided with your healthcare team and varies from person to person, so the diabetes team is the place to agree it.²³ See also Continuous glucose monitoring.

Total daily dose

Total daily dose is the total amount of insulin used across a whole day, adding together background (basal) and mealtime (bolus) insulin. A UK best practice guide for clinicians uses it as a starting point when estimating other pump settings, which the diabetes team sets for each person.^{34 39} See also Basal insulin, Bolus.

Transmitter

The transmitter is the small part of a continuous glucose monitoring system that sends readings from the sensor, without wires, to software on a smartphone, to an insulin pump or to a separate receiver. It is how sensor readings reach the screen or pump that shows them.³³ See also Sensor.

Tubing

Tubing is the thin, flexible tube in a conventional pump's infusion set that carries insulin from the pump towards the cannula under the skin. Diabetes UK notes the set can sometimes become blocked or unattached, while patch pumps have no extra tubing.^{22 40} See also Infusion set.

Type 1 diabetes

Type 1 diabetes is a condition where the body cannot make a hormone called insulin, which causes the level of glucose in the blood to get too high, according to the NHS. The American Diabetes Association adds that the immune system destroys the cells that make insulin.^{19 32} See also Insulin.

Type 2 diabetes

Type 2 diabetes is when insulin does not work properly or there is not enough of it, which makes the level of glucose in the blood too high, according to the NHS. NICE's 2008 pump guidance did not recommend pump therapy for type 2 diabetes.^{20 28} See also Insulin.

Unit of insulin

A unit is the standard measure of an amount of insulin. The American Diabetes Association explains that U-100 insulin means 100 units in each millilitre of solution, and UK pump guidance describes insulin amounts in units. Doses are set by a diabetes team.^{32 34} See also Insulin.