Diabetes Tech Glossary
Definitions for common terms used in continuous glucose monitoring and insulin pump therapy.
A
AID (Automated Insulin Delivery)
Also known as a closed-loop system. A system where a continuous glucose monitor (CGM) talks to an algorithm, which then commands an insulin pump to automatically adjust insulin delivery based on current and predicted glucose levels.
Active Insulin (IOB)
Insulin On Board. The estimated amount of bolus insulin from previous injections or pump deliveries that is still active in the body and working to lower blood glucose.
B
Basal Insulin
Background insulin delivered continuously to keep blood glucose stable between meals and overnight. In pumps, this is delivered as tiny micro-drops of rapid-acting insulin. In MDI, this is usually a once-daily injection of long-acting insulin.
Bolus
A larger, single dose of rapid-acting insulin given to cover carbohydrates eaten during a meal, or to correct a high blood glucose level.
C
CGM (Continuous Glucose Monitor)
A wearable device that measures glucose levels in the interstitial fluid (the fluid between cells) every few minutes, providing real-time data and trend arrows.
Carb Ratio (I:C Ratio)
Insulin-to-Carbohydrate ratio. The number of grams of carbohydrates that one unit of rapid-acting insulin will cover. For example, a 1:10 ratio means 1 unit of insulin covers 10 grams of carbs.
I
ISF (Insulin Sensitivity Factor)
Also known as Correction Factor. Indicates how many points (in mg/dL) one unit of rapid-acting insulin will lower blood glucose. For example, an ISF of 50 means 1 unit lowers glucose by 50 mg/dL.
Interstitial Fluid
The fluid surrounding the cells in tissue just under the skin. CGMs measure glucose here rather than directly in the blood. Interstitial glucose lags behind blood glucose by roughly 5-15 minutes.
M
MARD (Mean Absolute Relative Difference)
The standard metric used to measure CGM accuracy. It is the average percentage difference between the CGM reading and a reference blood glucose reading. A lower MARD indicates higher accuracy.
MDI (Multiple Daily Injections)
Managing diabetes with insulin pens or syringes rather than an insulin pump. Typically requires 1-2 basal injections and 3+ bolus injections daily.
T
TIR (Time in Range)
The percentage of time a person's glucose levels fall within the target range (standardized as 70-180 mg/dL). Clinical guidelines recommend aiming for >70% TIR.