# Time above and below (TAR)

Minutes above 7.8 and above 10.0; minutes below 3.9. Shown as minutes a day; VT counts exposure above 5.6 as a softer line.

Type: cgm_metric · Unit: min/day · Domain: Metabolic Health · Accuracy: Calculated · Importance: Supporting

Also called: time above range, time below range, minutes above 7.8, minutes above 10, minutes below 3.9, exposure above 5.6, glucose exposure, TBR

## In one sentence

How many minutes a day your glucose spent above 7.8, above 10.0, and below 3.9 mmol/L, and, as a softer line of VT's own, above 5.6.

## Why minutes

Percentages read badly near a ceiling: 2.1 percent of a day sounds like nothing, and it is 30 minutes. In 153 healthy people, time above 7.8 was a median of about 30 minutes a day and time below 3.9 about 15 (Shah 2019), and both are easier to picture as minutes than as decimals. The diabetes-care consensus sets its own targets in this unit's percentage form (for most adults with diabetes, under 25 percent above 10.0, under 4 percent below 3.9 and under 1 percent below 3.0; Battelino 2019); those are reported here as what they are, the clinical standard, not a scale for the reader.

## Why 5.6 as well

The 7.8 and 10.0 lines are far above where a healthy adult sits for most of the day, so a month's change in eating can leave them untouched. VT also counts exposure above 5.6 mmol/L (100 mg/dL), the figure many laboratories print as the top of the fasting reference range and the one the American Diabetes Association uses as the floor of its impaired-fasting-glucose band (ADA 2024). As a daytime line it is deliberately soft: everyone crosses it after meals, and the quantity worth watching is how many minutes a day, month against month.

## What moves it

Above: the same things as the mean, concentrated in the hours after meals. Below: alcohol in the evening, a long gap between meals, hard training, and, falsely, the night you lay on the sensor; most of a healthy person's minutes below 3.9 are nocturnal and some are artifacts (see the gotchas).

## How Vitality Tracker uses it

Calculated per day and per period, shown as minutes with the four lines named. Not a Vitality Score input.

## How far to trust the number

Calculated from measured readings; the minutes above the high lines are robust, the minutes below 3.9 are the least trustworthy figure on the shelf, because a sensor's lows are where lag and compression do their work.

## Method

For each line, count of readings beyond it × 5 minutes, per day; period figures are daily means. Lines: 5.6, 7.8, 10.0 (above); 3.9 (below).

## Sources

1. Shah VN, et al. J Clin Endocrinol Metab 2019;104:4356–64. [doi:10.1210/jc.2018-02763](https://doi.org/10.1210/jc.2018-02763)
2. Battelino T, et al. Diabetes Care 2019;42:1593–603. [doi:10.2337/dci19-0028](https://doi.org/10.2337/dci19-0028)
3. American Diabetes Association. 2. Diagnosis and classification of diabetes: Standards of Care in Diabetes 2024. Diabetes Care 2024;47(Suppl 1):S20–42. [doi:10.2337/dc24-S002](https://doi.org/10.2337/dc24-S002)
4. Vitality Tracker, Knowledge Base brief, catalogue D.

## Related

- [Time in tight range](https://vitalitytracker.app/knowledge/time-in-tight-range)
- [Time in range](https://vitalitytracker.app/knowledge/time-in-range)
- [Fasting glucose](https://vitalitytracker.app/knowledge/fasting-glucose)
- [Reading a CGM without fooling yourself](https://vitalitytracker.app/knowledge/reading-a-cgm-without-fooling-yourself)
- [Mean glucose](https://vitalitytracker.app/knowledge/mean-glucose)

Reviewed October 2026 · v1

Source: https://vitalitytracker.app/knowledge/time-above-and-below