Free reference

T1D glossary

35 terms from CGM reports, insulin pumps and the clinic, each with the consensus paper, guideline or maker page that defines it, quoted.

15-15 rule: The 15-15 rule is the CDC's published way to treat a low: have 15 grams of carbs, wait 15 minutes, then check again.
A1C (HbA1c): A1C is a blood test that measures how much hemoglobin has glucose attached.
Ambulatory Glucose Profile (AGP) report: The AGP report is a standard summary of CGM data, developed by the International Diabetes Center.
Basal insulin: Basal insulin is the steady background insulin that covers the body's needs between meals and overnight.
Bolus: A bolus is a single dose of rapid-acting insulin on top of basal insulin.
Carbs on board (COB): Carbs on board is an estimate of how many grams of a logged meal have not yet been absorbed.
Closed loop (automated insulin delivery, AID): A closed-loop system links a CGM, an insulin pump and an algorithm that raises or lowers insulin delivery based on CGM values.
Coefficient of variation (CV): CV measures how much glucose swings, relative to its average: the standard deviation divided by the mean.
Compression low: A compression low is a false low on a CGM caused by pressure on the sensor site, most often from lying on it while asleep.
Continuous glucose monitor (CGM): A CGM is a small sensor worn under the skin that estimates glucose every few minutes and keeps track of it over time.
Dawn phenomenon: The dawn phenomenon is a rise in glucose toward the end of the night, with no low before it and no food.
Diabetic ketoacidosis (DKA): DKA is a serious and life-threatening complication in which the body, short of insulin, breaks down fat for fuel and ketones build up in the blood.
Estimated A1C (eA1C): Estimated A1C converts a mean glucose from CGM or fingersticks into a value on the A1C scale.
Follower: A follower is a person who sees someone else's CGM numbers on their own phone or watch, such as family and friends.
Glucagon: Glucagon is a hormone that raises blood glucose.
Glucose management indicator (GMI): GMI turns the mean glucose from CGM data into a number on the A1C scale.
Glycemia Risk Index (GRI): GRI is one score from 0 to 100 that combines time in the four out-of-range bands, with lows weighted more than highs.
Honeymoon phase: The honeymoon phase is a period soon after a type 1 diagnosis when the pancreas makes more of its own insulin again, once insulin treatment has brought glucose down.
Insulin on board (IOB): Insulin on board is the insulin from earlier doses that a pump or app estimates is still working.
Insulin sensitivity factor (ISF): The insulin sensitivity factor, also called the correction factor, is how far one unit of insulin is expected to lower glucose, in mg/dL or mmol/L.
Insulin-to-carbohydrate ratio (ICR): The insulin-to-carbohydrate ratio is the number of grams of carbohydrate that one unit of insulin covers.
Ketones: Ketones are acids the liver makes when the body burns fat for fuel because there is not enough insulin.
Level 1 hypoglycemia: Level 1 hypoglycemia is glucose under 70 mg/dL (3.9 mmol/L) and at or above 54 mg/dL (3.0 mmol/L).
Level 2 hypoglycemia: Level 2 hypoglycemia is glucose under 54 mg/dL (3.0 mmol/L).
Level 3 hypoglycemia: Level 3 hypoglycemia is a severe low in which the person's thinking or movement is affected so much that someone else has to help them recover.
MARD (mean absolute relative difference): MARD is the most common number used to describe CGM accuracy.
Nightscout: Nightscout is an open-source cloud app that people with diabetes and parents of kids with diabetes use to store, view and share CGM data in real time.
Pre-bolus: A pre-bolus is a meal bolus given some minutes before eating, so the insulin starts working closer to when the meal raises glucose.
Sensor warm-up: Sensor warm-up is the wait after a new CGM sensor goes in, before it shows glucose values and alerts.
Signal loss: Signal loss is when the phone or receiver stops getting values from the CGM sensor.
Somogyi effect: The Somogyi effect is the idea, first reported by Michael Somogyi, that a low during the night leads to a high fasting glucose the next morning.
Time above range (TAR): Time above range is the share of CGM values over 180 mg/dL (10.0 mmol/L).
Time below range (TBR): Time below range is the share of CGM values under 70 mg/dL (3.9 mmol/L).
Time in range (TIR): Time in range is the share of CGM values, and of the day, that falls between 70 and 180 mg/dL (3.9 to 10.0 mmol/L).
Time in tight range (TITR): Time in tight range is the share of CGM values between 70 and 140 mg/dL (3.9 to 7.8 mmol/L), a narrower band than standard time in range.