Most reviews of an ambulatory glucose profile collapse two weeks into a single 24-hour curve. That is the right place to start, but it hides a pattern almost every clinician has seen and few write down: control that is steadier on working days and drifts at weekends, with the evening and overnight hours carrying most of the trouble.
It matters because two quite different fortnights can produce the same average time in range. If the shortfall is concentrated on Saturday and Sunday evenings, the fix is behavioural — meal timing, alcohol, an unstructured day — and not a change in basal dose. Increase the basal to cover a weekend pattern and you buy hypoglycaemia on Tuesday.
So split the report before you touch the regimen. Look at weekdays and weekend days separately, and look at the evening and overnight window separately from the daytime. Then ask the patient to describe what a Saturday actually looks like. The answer usually explains the curve faster than any dose calculation does.
- Ask for at least 14 days of data with 70% or more sensor wear before drawing any conclusion from a pattern.
- Compare weekdays and weekend days separately before changing a dose.
- Look at the 6 pm to 6 am window on its own — it is where most of the lost time in range usually sits.
- Ask the patient to walk you through a typical weekend day, including meal times and alcohol.
- If a pattern is confined to two days a week, change behaviour or bolus timing, not the basal dose.
The statistics, in plain English
Fourteen days of wear with at least 70% sensor coverage is the usual minimum for an ambulatory glucose profile to represent longer-term control. Splitting that period by day of week leaves only four or five days in each arm — enough to spot a consistent pattern, not enough to trust a small difference. If weekday and weekend curves differ by a couple of percentage points of time in range, treat it as noise. If the weekend curve sits visibly lower and does so across two separate sensor periods, it is real.
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