The Scientific Method – Part 1

Diabetes data


My little notebook of diabetes and exercise details is turning out to be really helpful. (My own diabetes software tools have been invaluable at aggregating all of the information and helping me retrospectively look at it.) Tuesday night I gathered all of the data I had written down about my diabetes and swimming. Here it is.

2014-12-03 AM: 0.0u IOB -   0g        -  1:03 -->  -3 mg/dL (outlier?)
2014-12-05 AM: 0.0u IOB -   8g @-0:10 -  0:58 -->  -9 mg/dL
2014-12-30 AM: 0.0u IOB -  26g @-0:20 -  0:44 --> +52 mg/dL (Easy day)
2015-02-11 AM: 0.0u IOB -   0g        -  1:00 --> -65 mg/dL
2015-02-13 AM: 0.0u IOB -  41g @-0:20 -  0:24 --> -30 mg/dL (outlier?)
2015-04-06 AM: 0.3u IOB -   0g        -  0:30 --> -62 mg/dL
2015-04-08 AM: 0.3u IOB -  25g @-0:15 -  0:58 --> +11 mg/dL 
2015-04-10 AM: 0.3u IOB -   0g        -  1:01 --> -76 mg/dL
2015-04-13 AM: 0.0u IOB -   0g        -  1:07 --> -66 mg/dL

I noticed a trend and made this hypothesis: “If I don’t eat and have no insulin on board (IOB), then my blood glucose seems to drop about 1 mg/dL for each minute I swim.” Along with this related hypothesis: “If I eat about 20-25g of carbohydrate, I go up just slightly when I swim for an hour.” I resolved to test one of these based on what the morning presented.

After an otherwise very stable night of blood sugars in the low 100s, I woke with a 172 mg/dL on my meter. “Time to check the ’1 mg/dL/minute without food’ hypothesis, ” I thought. I swam for 1:04. The workout was fairly tough: 2,800 yards total with a main set of 4×500 yards, descending in time with each 500. On the last one I was supposed to hold my “best 300″ pace for the full 500 yards. I didn’t quite make it. Like I said, it was a tough one. Oh well.

My BG at the end of the hour-long swim was 110 mg/dL. Over 64 minutes of swimming, my BG fell 62 mg/dL. Sounds like more evidence in support of the hypothesis! :-)

Before my run on Wednesday afternoon I decided to try another experiment (n=1) based on my results when I run.

2014-10-05 AM: 0.0u IOB -  20g @+0:22 -   65% basal @-0:20 -  0:48 --> +10 mg/dL
2014-12-04 AM: 0.0u IOB -   0g        -  100% basal        -  0:52 --> -15 mg/dL
2015-02-14 AM: 0.0u IOB -  25g @-2:00 -   60% basal @-2:00 -  0:36 --> -95 mg/dL
2015-04-03 AM: 0.0u IOB -  25g @-0:30 -  100% basal        -  0:34 --> +40 mg/dL
2015-04-07 PM: 0.2u IOB -   0g        -   60% basal @-2:15 -  0:45 --> -16 mg/dL
2015-04-09 PM: 0.3u IOB -   0g        -   60% basal @-2:15 -  0:30 --> -18 mg/dL
2015-04-11 AM: 0.0u IOB -   0g        -  100% basal        -  1:00 --> -28 mg/dL

I hoped that if I ran about 45 minutes in the afternoon with a tiny bit of active insulin but no food, I wouldn’t see much of of drop. Unfortunately, that’s not how it turned out:

2015-04-15 PM: 0.4u IOB -  0g -  60% basal @-1:45 -  0:51 --> -106 mg/dL

Oh, well. More data.

This entry was posted in Data-betes, Diabetes, Running, Swimming. Bookmark the permalink.

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