Layering every day's glucose readings for an entire year, I'm able to search for patterns in daily trends. On the far left is 12am, on the far right 12pm. In between, faint patterns and trends emerge to the eye.
I've taken the glucose readings from each hour (4am-5am, 5am-6am and so on) and computed the median value from these readings to form the bold line in the center. This line represents my trend line for glucose across any given day in the year. Toggling between the years provides an interesting look at the shift in daily metabolism.
For hours with fewer than 50 readings for the year (typically early mornings and late nights), I add the median for all values to pad the mean for these early hours, effectively tempering the overnight bumps. Usually the only time I would test at these hours is if I woke up and something felt "off", no sense skewing the graph for a few overnight highs ;)