# Largest amplitude of glycemic excursion (LAGE)

The day’s highest reading minus its lowest; one number per day.

Type: cgm_metric · Unit: mmol/L · Domain: Metabolic Health · Accuracy: Calculated · Importance: Supporting

Also called: largest swing, glucose range, daily glucose range, max minus min

## In one sentence

The day's highest reading minus its lowest: the size of the biggest swing, one number per day, with nothing to work out.

## Why it matters

It is the easiest variability figure to picture and the one most people check first: how far apart were my best and worst moments today? A day with a LAGE of 3 mmol/L had a quiet range; a day with 6 had a large meal or a hard session in it, or both. It is also the most fragile figure on the shelf, because one false reading at either end sets it.

## What moves it

The single biggest meal or the single hardest session of the day sets the top; the night, or a long gap between meals, sets the bottom. A compression low at 3 a.m. can double it, which is why VT takes flagged readings out before it is computed.

## How to read it well

As a daily companion to the meal log: the day's LAGE and the meal that caused it. For a period, read the median of the daily values rather than their maximum.

## How Vitality Tracker uses it

Calculated per day from valid readings; the period figure is the median of the days. Not a Vitality Score input.

## How far to trust the number

Calculated from two measured readings, the two most likely to be wrong; the artifact filter does most of the work of making it trustworthy.

## Method

LAGE = max(valid readings in the day) − min(valid readings in the day).

## Sources

1. Vitality Tracker, Knowledge Base brief, catalogue D; the definition is arithmetic and has no primary source beyond common use in the CGM literature.

## Related

- [Mean amplitude of glycemic excursions](https://vitalitytracker.app/knowledge/mage)
- [Standard deviation of glucose](https://vitalitytracker.app/knowledge/glucose-standard-deviation)
- [Peak rise](https://vitalitytracker.app/knowledge/peak-rise)
- [Reading a CGM without fooling yourself](https://vitalitytracker.app/knowledge/reading-a-cgm-without-fooling-yourself)

Reviewed October 2026 · v1

Source: https://vitalitytracker.app/knowledge/lage