The photo is from my Freestyle Libre continuous glucose monitor (CGM)
Everything is a wave, our heartbeat, our breathing, brain waves, even thoughts go up and down with emotion just like a wave. The stock market is said to rise and fall between fear and greed. Tides come in and go out, which is another wave. Sunrise to sunset, light to dark, all waves. So it is not really surprising that I love hills as they are such an easy to feel wave. The undulations are familiar and sensual.
The photo corresponds to a day of my blood glucose (BG) numbers from my CGM which I use because I am a type 1 diabetic. A non-diabetic’s BG is under 100 when fasting (before breakfast) and does not go over 140 after meals. However, even non-diabetics will have higher BG spikes if they eat a lot of sugar or starch. Basically, eating makes BG go up and insulin must be taken with meals to make it go down. Exercising makes BG go down and usually allows for taking less insulin. A little bit of a bumpy hill that takes planning.
It is probably illegal for me to give advice about how to balance BG while riding hills. However, only a diabetic can really understand the intricacies of the rises and falls of BG. Now try to find a diabetic doctor who also rides hills. You may be searching for awhile. So I will just write about what I do and not give advice. My only advice would be just be careful. After all, diabetics all react differently to various foods or different insulins or individual fitness levels. Also note that I probably ride slower than you do as some pretty unlikely riders are passing me these days.
The first “hill” in the graph happens around 6 in the morning. When I wake up I have a large dawn effect which happens when the liver releases a large amount of sugar into the blood stream to get me ready for the day. Usually I either eat nothing for breakfast or a protein only breakfast. Even though I have eaten no carbohydrates for breakfast, such a large sugar release by the liver requires that I take insulin. Now some will immediately question whether skipping breakfast is good advice. It is not advice but it is just what I do. Still, there is a large body of evidence that shows this type of intermittent fasting has beneficial effects. I had to get used to fasting like this gradually and it is now part of my routine.
The hill starts to decline around 8 in the morning because that is when I take a walk. Walking causes declines in BG even without taking insulin because it allows the glucose to enter the muscles without insulin. Exercising, besides the fact that I like it, allows me to use a little less insulin but does not eliminate the need for insulin.
The next BG hill happens just before 12 noon when I eat lunch. I was planning to ride shortly after lunch so I take only about 70% of the insulin I normally take. This results in a rather rapid rise toward a BG of 150 which is what I intended. When I am going to ride hills I don’t start until my BG is at least 150 because hill riding causes rapid declines in BG. Don’t start with BGs under 100 or you won’t even make it up the first hill. It was a 2 hour hill ride and I spent most of the time around 150 BG. Then because of the hard hills and the insulin I had taken for lunch, the BG continued to decline for another 2 hours after the ride until 5 in the afternoon. These declines are something that has to be planned for so as not to go too low.
One thing that has given me confidence to ride hills like this is my Freestyle Libre CGM. I can tell at any minute whether my BG is going high or low and how fast, just by looking at the app on my phone. I never had this kind of data in the past when I used to use finger stick testing only ever 3-4 hours because that only shows one point in time. Thank you Abbott Labs Freestyle, you have made hills fun again.