Glossary of Common Diabetes Terms

A1c (Hemoglobin A1c / HbA1c)

A test that measures the average blood glucose level over the past 2 to 3 months. It reflects the amount of glucose that is attached to a red blood cell, expressed in percentage (%).

AHCL Advanced Hybrid Closed Loop system.

AHCL systems are differentiated from a standard Hybrid Closed Loop system (HCL) by the ability to deliver automatic correction boluses. Currently, the only approved AHCL system is the t:slim X2 insulin pump with Control-IQ technology.

AID Automated Insulin Delivery

Term used to describe any system where an insulin pump is able to adjust insulin delivery based solely on input from a CGM or other data source, without user intervention.


A set of rules for solving a problem. In diabetes, it usually refers to the rules governing how an automated insulin delivery (AID) system decides when and how much insulin to deliver.

Artificial Pancreas

A broad term generally understood to mean a closed-loop AID system, although it has been used inconsistently over the years. Tandem Diabetes Care does not use this term to describe any of our current or future AID systems.


A slow continuous delivery of insulin, which keeps blood glucose level stable between meals and during sleep. A basal rate is measured in units per hour.

Basal-IQ Technology

A predictive low glucose suspend system (PLGS) from Tandem Diabetes Care that uses the Dexcom G6 CGM.

BG (Blood Glucose / Blood Sugar)

The level of glucose in the blood, measured in mg/dL.
Bionic Pancreas

A proprietary name for an automated insulin delivery (AID) system developed at Massachusetts General Hospital and currently part of Beta Bionics.


A quick dose of insulin that is delivered to cover food consumed or elevated blood glucose.

The tiny, flexible section of the infusion set that is inserted under the skin and through which insulin is delivered.

Carb Ratio (Insulin-to-Carbohydrate Ratio)

The number of grams of carbohydrate that one unit of insulin will cover.

Carbohydrate (Carb)

Sugars and starches that the body breaks down to glucose and uses as an energy source, measured in grams.

Carbohydrate Counting

A method of meal planning based on counting the grams of carbohydrate in food.


The disposable component of the Tandem pump that holds the insulin.

Certified Diabetes Educator (CDE)

A healthcare professional that has experience working with diabetes, has fulfilled special requirements, and passed a board exam to be certified to instruct people in diabetes self-management.

CGM (Continuous Glucose Monitor)

A continuous glucose monitor (CGM) is a handheld personal monitoring device that uses wireless technology to collect glucose readings from a small sensor inserted under the skin.

Closed Loop

A term describing a system that can regulate itself without operator intervention. In diabetes it is used to descibe a system that can regulate blood glucose without a user needing to enter glucose or carbohydrate values. True closed-loop systems in diabetes do not yet exist.

Closed Loop Control (CLC)

Generally used as a measure of how much time an automated insulin delivery (AID) system is actively adjusting insulin delivery. It is often expressed as a percentage.

Control-IQ Technology

Control-IQ technology is an advanced hybrid closed-loop system that uses Dexcom G6 CGM values to predict glucose levels 30 minutes ahead and adjusts insulin delivery accordingly, including the delivery of automatic correction boluses as needed.

Correction Bolus

A dose of insulin given to correct an elevated blood glucose level.

Correction Factor (Insulin Sensitivity Factor)

The amount of blood glucose (mg/dL) that is lowered by one unit of insulin.

Dawn Phenomenon

A rise in blood glucose levels in the early morning hours caused by an increase of hormone.

Diabetic Ketoacidosis (DKA / Ketoacidosis)

An emergency condition in which extremely high blood glucose levels, along with a severe lack of insulin, result in the breakdown of body fat for energy and an accumulation of ketones in the blood and urine.

Dual Hormone

An automated insulin delivery (AID) system that uses two hormones to help regulate blood glucose instead of just insulin. There are currently no dual-hormone systems available.

Duration of Insulin Action (DIA / Insulin Duration)

The amount of time that insulin is active and available in the body after a bolus has been delivered. It is also used in the calculation for Insulin on Board (IOB).


A physician that is board certified to treat hormone-related conditions including diabetes.

Extended Bolus

A bolus that is delivered over a set period of time.

Food Bolus

A dose of insulin that is taken before meals or snacks to cover the expected rise in blood glucose from the food. Food boluses are typically matched to the carbohydrate content of the food.


A condition that slows stomach emptying and digestion.

Gestational Diabetes

A diabetes that is diagnosed during pregnancy.


A hormone secreted by the pancreas that acts in opposition to insulin in the regulation of blood glucose levels. Some experimental dual-hormone automated insulin delivery (AID) systems have used glucagon and insulin as the two hormones.

Glucagon Emergency Kit

A kit containing glucagon (a hormone that quickly increases blood glucose) and a syringe used to treat severe hypoglycemia. Glucagon requires a prescription and is administered as an injection by someone else.


The primary source of energy for the body that breaks down from food, mostly carbohydrate, and is also produced by the liver. It is often referred to as blood sugar.

Glucose Reminder

An insulin pump feature that can be set to remind the user to check glucose within a specific time following a high- or low-glucose event.

Glycemic Index

A system that ranks carbohydrate foods according to how much they raise glucose compared with a reference food.

Glycemic Load

A system that considers both serving size and the Glycemic Index to determine the food’s effect on glucose.


The stored form of glucose found in the liver and muscles.

HCL Hybrid Closed Loop.

A term used to describe automated insulin delivery (AID) systems where basal insulin is controlled by the system, but not bolus insulin.


High blood glucose or high blood sugar.


Low blood glucose, low blood sugar, or insulin reaction.

Hypoglycemia Unawareness

A state in which a person does not feel or recognize the symptoms of low glucose.


The automated insulin delivery (AID) algorithm developed at UVA which became the basis for the Control-IQ advanced hybrid closed-loop system.

Infusion Set (Insertion Set)

A complete tubing system that is attached to the end of the cartridge of the pump and connects to the body at the infusion site, through which insulin is delivered.

Infusion Site (Insertion Site)

The area on the body into which the cannula or needle are inserted.

Injection / Infusion Site Rotation

Changing the places on the body where insulin is injected. This applies to either syringe injections or insulin pump infusion sets. Rotation prevents the formation of lipodystrophies (defects in the breaking down or building up of fat below the surface of the skin), which can result in lumps or small dents in the skin surface.

Insertion Device

A device used to insert the cannula under the skin.


A hormone, produced by beta cells in the pancreas, that helps the body use glucose for energy.

Insulin Duration

The amount of time that insulin is active and available in the body after a bolus has been delivered. It is also used in the calculation for insulin on board (IOB).

Insulin on Board

Reflects how much insulin is remaining in the body from a previous bolus (or boluses) that will continue to lower glucose. It is also referred to as active insulin or bolus on board.

Insulin Pump

A small medical device that delivers precise amounts of short- or rapid-acting insulin into the body in the treatment of diabetes. The two modes of delivery are basal and bolus.

Insulin Resistance

A condition that makes it harder for the cells to properly use insulin. Occurs in type 2 diabetes before the body stops producing enough insulin.

Insulin Stacking

Occurs when multiple boluses of insulin accumulate in the blood and may lead to hypoglycemia.

Intermediate-Acting Insulin

A type of insulin that starts to lower blood glucose within 1 to 2 hours after injection and has its strongest effect 6 to 12 hours after injection, depending on the type used.

Introducer Needle

A small needle used to insert the cannula under the skin and that is removed after insertion.


A waste product that accumulates when glucose is not available and fat is used for energy.
Lancet A fine, sharp-pointed needle for pricking the skin to obtain a drop of blood for glucose monitoring.

LGS Low Glucose Suspend.

A term for early automated insulin delivery (AID) systems that shut off insulin delivery when CGM values dropped below a given level. Also called Threshold Suspend systems.

Long-Acting Insulin

A type of insulin that starts to lower blood glucose levels within 1 hour after injection and works evenly for 12 to 24 hours after injection. This is replaced with very small doses of rapid-acting insulin delivered as basal insulin with pump therapy.

LTS Low Threshold Suspend.

A term for early automated insulin delivery (AID) systems that shut off insulin delivery when CGM values dropped below a given level. Also called Threshold Suspend or Low Glucose Suspend systems.


The abbreviation for milligrams of glucose per deciliter of blood (unit for measuring blood glucose levels).

Missed Meal Bolus Reminder

A programmable setting to notify the user of a possible Missed Meal Bolus.


Disease of the kidneys caused by damage to the small blood vessels that may occur due to prolonged high blood glucose. People with diabetes should be monitored annually to detect early changes in the kidneys.

Net Carbs (Impact Carbs, Active Carbs)

Terms used on food labels indicating that all of the fiber and sugar alcohol have been subtracted from the Total Carbohydrate. These terms are not regulated by the FDA.


Nerve damage that may be caused by prolonged high exposure to high blood glucose. This can cause pain, numbness, and tingling (especially in the hands or feet), impotence, silent cardiac conditions, and slower-than-normal digestion.


A clog or blockage associated with the infusion set and/or infusion site that can stop or slow insulin delivery. An occlusion is typically caused by the cannula being pinched, kinked, dislodged, or blocked by the formation of insulin crystals.


An organ located behind the lower part of the stomach. The beta cells in the pancreas produce the hormone insulin.

Personal Profile

A personalized group of settings that define the delivery of basal and bolus insulin within specific time segments throughout a 24-hour period.

PLGS Predictive Low Glucose Suspend system.

Similar to LGS, except insulin delivery is shut off based on predicted glucose values, not current values.

Quick Bolus

A secondary way to deliver a bolus by following vibration and beep commands without navigating through or viewing the insulin pump screen.

Rapid-Acting Insulin

A type of insulin with the most rapid onset (10 minutes), that works more quickly at lowering your blood glucose.


A disease of the small blood vessels in the retina of the eye that may be caused by prolonged high blood glucose. A person with diabetes should be monitored on an annual basis to detect any changes and receive treatment to prevent loss of vision.

Safety Study

A clinical study designed to test the safety of a drug or device, but which isn't powered to evaluate its clinical benefits.

Short-Acting Insulin

A type of insulin that starts to lower blood glucose within 30 minutes after injection and has its strongest effect 2 to 5 hours after injection.

Site Reminder

A programmable setting to remind the pump user when it is time for an infusion set to be changed.

SMBG (Self-Monitoring of Blood Glucose)

Checking blood glucose with a blood glucose meter. This behavior should be accompanied by a plan of action to respond to the results and discussed with the healthcare professional treating the diabetes during each visit.

Somogyi Effect (Rebound Effect / Rebound Hyperglycemia)

A condition in which counter-regulatory or stress hormones are released in reaction to a low blood sugar and cause the liver to release too much glucose resulting in a rebound hyperglycemia. Typically occurs overnight and tends to cause high blood glucose levels.

t:lock™ connector

Connects and locks the infusion set tubing to the insulin pump cartridge.

Target Glucose

A specific glucose goal used to calculate a Correction Bolus.

Target Range

Target range is described in the American Diabetes Association’s Standards of Care as the ideal glucose range for people with diabetes, and is defined as between 70mg/dL and 180 mg/dL.

Temporary Rate

A feature in the insulin pump that allows a short-term adjustment to the basal rate.

Threshold Suspend

A term for early automated insulin delivery (AID) systems that shut off insulin delivery when CGM values dropped below a given level. Also called Low Threshold Suspend or Low Glucose Suspend systems.

Time in Range

A metric often used to evaluate the effectiveness of a given treatment method, time in range is generally understood to mean the time spent between 70 and 180 mg/dL in a 24-hour period. It is often expressed as a percentage.

Time Segments

Specific time periods within a Personal Profile where basal rates, correction factors, carb ratios, and target glucose values are set.

Treatment Value

Treatment values are the predicted CGM values that trigger Control-IQ technology to act in order to help increase time spent in the target range.


A flexible tube that allows insulin to flow from the pump to the infusion site.

Type 1 Diabetes

A condition in which beta cells in the pancreas are destroyed, preventing the body from producing insulin. People with type 1 diabetes must use insulin to treat this. Formerly known as Juvenile Onset Diabetes or Insulin-Dependent Diabetes Mellitus, IDDM.

Type 2 Diabetes

A condition in which the pancreas either makes too little insulin or the body loses the ability to use the insulin it produces. Over time, the pancreas may stop producing insulin. Type 2 diabetes may be treated with lifestyle changes (healthy eating and physical activity), oral medications, insulin, or other injectable medications. Formerly known as Adult-Onset Diabetes or Non-Insulin Dependent Diabetes Mellitus (NIDDM).


TypeZero is a company created to commercialize the work done at the University of Virginia on the inControl algorithm, which is the basis of Conttrol-IQ technology. TypeZero was acquired by Dexcom in August of 2018.

Units (of Insulin)

Measurement of insulin volume.

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