This is a data visualization I produced during the Fall 2011 term at ITP. I used 7729 readings from my Dexcom 7 CGM (continuous glucose monitor) from November, 2011. I created it using Processing, then generated a PDF showing the entire month’s readings on top and additional PDFs for every individual day of the month below. The circle spans the respective time frames starting at the top (12:00), progressing clockwise one turn. The blue represents in-range readings (80-140 mg/dL). The gray represents low blood sugar readings (79-40 mg/dL) and the outside white contains all the high blood sugars readings above 140 mg/dL.
With an A1c of 6.5%, I consider myself to have good control. Of course I am aware that my blood sugar goes high some times, especially after meals. But at first glance I was quite surprised at the amount of volatility in the readings. There are fewer days than I expected where my blood sugars were in range the majority of the time. If you look closely, November 5th was my best day. Thanksgiving Day on November 24th was my worst day. In case all the turkey and mashed potatoes was not enough, I had come down with the flu the day before. This often results in unusual blood sugar readings as well.
For the month view, I presented the data this way to give a medium-range view of my control. It was not to see what specific changes needed to be made, but rather to answer the simple question, “How was your control this month?” With so much volatility, I can see that I still have a lot more work to do, even with a good A1c reading.
With the day views, I can see specific times when the blood sugar changed. If I can combine this with a more complete data set including nutritional information, I will have specific information about the cause of the spikes. With that, I can work on a specific solution.
I learned quite a bit in producing this visualization (you can read more about that here and here). It is certainly easier to understand this display than a list of data points and statistics about average blood sugars. I already have ideas on future iterations and integrating this view into a more complete system. Check back throughout 2012 to see more.