Interesting info about and thoughts on the feet-on-floor phenomenon and dusk phenomenon


I guess I thought of them as all part of the same continuum, but I take your point.

YES! Drives me nuts. “High” and “low” have special meanings in the D context, so there’s a confusing ambiguity there. References to “setting your I:C ratio higher” and the like always stop me in my tracks for some head-scratching. Because the context is all about insulin usage, I tend to assume it refers to the insulin part, so a “higher” ratio is one where the amount of insulin you have to take for a certain # of carbs is “higher” than a “lower” one. In which case, yeah, 1:6 is “higher” than 1:12, because if your meal is, say, 36 carbs, it’s the difference between taking 6 units vs only 3 units. But I’m never sure the person saying it means what I think they mean, so I prefer if people just give me the numbers and skip the terminology.

OT, so I’ll save it for another thread, but I have a similar mini-rant about the ambiguity of “diabetic coma” when it appears in the media or common parlance—I know what I think it refers to but is that what they are referring to?


I agree. So regardless of which is correct, I try to avoid using the higher or lower term in regards to the I:C as the meaning is easily lost on the audience regardless of the correctness or not.

I prefer to say things like:
I am changing the I:C from 1:10 to 1:8 so as to provide more insulin with the food.

Bottom line is avoiding confusion. Even in my own head.


Our basal profile has a 40% increase from 5AM to 8AM. That seems to work pretty good for us.

Obvious [unresolved] issue is school days vs weekend days.


I’ve found that people are often confused about inverse mathematical relationships. How many times have we all run into the social confusion about how to treat a person passed out from hypoglycemia? My former coworkers often asserted that I needed insulin! Insulin and blood sugar move in an inverse relationship.

Remember the grade school math teachers who tried to tell us about the difference between direct and inverse variation? The human brain certainly gets the direct variation but trips over the inverse one.

I agree with @Tim35. It’s better to communicate about the ultimate effect.

You can also say things like, “I’m making my basal rates more aggressive or less aggressive.” Adding that you will be adding or subtracting insulin makes a clear conclusion. I think verbally stepping around the inverse relationship trap and using clear narrative terms is the best solution. I don’t think the confusion over inverse math relationships will ever be fixed in the general population.


Some updates. I have been successful in handling the feet-on-floor phenomenon in the way I described. However, I have to refine my description a bit.

One tricky part of this phenomenon is that the BG rise actually does not kick in immediately after I stand up. Rather, getting up starts a process that takes a while to kick in. I’ve observed this with my CGM. About 40-60 minutes after standing up, the BG rises, and when it does, it does so rather sharply. That’s what is tricky about it: After 40-60 minutes, you suddenly need a bolus insulin, at peak activity. This means that the first 40 minutes or so, you may go low if you injected in bed before standing up. And yet, if you inject 40 minutes after getting up, then the bolus won’t catch up in time.

The solution I found was to combine the feet-on-floor bolus (2 units in my case) with the breakfast. So, I bolus for both , with one injection. I do the usual pre-bolus for the breakfast, so after injecting, I wait 10-15 minutes before I start eating. The idea here is that by having breakfast, I avoid lows in the first 40 minutes after getting up. And by pre-bolusing, I make sure the breakfast does not spike my BG too much. Result: Moderate BG rise from the breakfast, and no BG spike from the feet-on-floor phenomenon.

I also found more info about this phenomenon: The cortisol awakening response is responsible for it. Since it occurs in most people, it is no wonder that most of us T1s have it.

I talked to a couple of very experienced T1s about this. Some of them even studying endocrinology. What you experience could easily be a cause of “correlation, not causation”. When you get up, the cortisol response starts to kick in, but delayed, as described. So you take a while to get going, the coffee’s brewing, 30-50 minutes can easily pass by. Then you drink your coffee, about 40-50 minutes have passed, and you see a BG rise. You think it is the caffeine, but actually it might be the cortisol response. The correlation is the timing - you happen to drink the coffee at the same time when the cortisol level surges, and that’s because both events (cortisol response and breakfast) start at the same time and roughly have the same timings.

One explanation I got was that dawn phenomenon is mainly driven by growth hormone, while feet-on-floor is driven by the aforementioned cortisol response. So, different hormones are responsible. Early morning growth hormone spikes are highest in teenagers and kids. And that is the age range where the dawn phenomenon is strongest. (This is also why kids often get issued a pump right away these days, at least in some countries.)

I do wonder if getting T1D early somehow inhibits a natural development that turns off growth hormone spikes later in life after puberty’s over. I have observed that apparently, DP is much less likely to occur in LADAs like me compared to juvenile-onset T1D.


Yes, I’ve considered that possibility too. Not the ideal test condition but I did recently have a c-scope scheduled at 9am, and so had no coffee (or anything) beforehand. Just kept my basal settings at their standard values and didn’t bolus. Everything remained steady from getting up through the procedure, BG tested at 109 in the prep room, about 110 after. Not ideal circumstances, like I say, since I was up multiple times through the night (yay c-scope prep, ugh), which probably messed up my whole hormonal/diurnal balance, but fwiw. A better test would be to skip coffee and see what happens, but damn. I mean, coffee

Anyway, interesting stuff, very illuminating post.


@Tim35 - Thank goodness for the pump. My basal rate triples between 3:30am and 7, all in anticipation of wakeup DP (&/or Feet on Floor phenomenon) at 5AM.


I use an automated insulin dosing system and my background basal rates are essentially flat through the 24-hour day. I let the algorithm respond to increased insulin needs caused by dawn phenomena and other factors.

I do have a need for more basal insulin within the hour or two after I get up. Note above the active insulin (insulin on board) bump created by DP. I woke up at 4:30 this morning.

Before I started using an automated system, I also had programmed into my pump a significant basal rate jump, often starting around 3:00 a.m.


I have found noticeable differences with this by using the blue light filter on my phone and not watching tv at least an hour before bed. I really believe that by trying to eliminate as much of the blue light after dusk as you can it helps keep your cortisol levels lower over night and into the morning.


This sounds plausible. It would be interesting though to see what the cause of the improvement is. I see two possible ones, perhaps both apply:

  1. Cortisol surges are tightly related to the intensity of incoming blue light. That’s one reason why people who work late in the day experience a “second wind” effect - it is another cortisol surge, triggered by blue light.

  2. Absence of blue light allows melatonin to be released. Melatonin is also known as the “sleep hormone”, indicating why it is important. By abstaining from blue light about half an hour to an hour before bed, you allow melatonin to kick in. This improves your sleep quality. In other words, you are doing sleep hygiene. Better sleep means less cortisol released in the next day.

EDIT: I also want to point out that cortisol is being given a bad rep here. Cortisol has its place, and is not a “bad guy”. In fact, without the cortisol awakening response, waking up and getting up would probably be more difficult. The waking-up process is apparently rather energy intensive, so it is useful to get a jolt in the morning. We just have to handle it manually. Furthermore, the concept of such a “jolt” is also interesting in combination with sleep quality: If you sleep well, you need less energy to wake up. Bad sleep means your body is not fully recovered, you are fatigued, and need more energy to get going.


This looks amazing! Is this Loop? I bet that DP would have surged well into the 200s without that insulin shot.


@athx9891 - Yes, I’m using Loop. It continues to amaze me, even at 26 months in. I woke up at 72 (4.0) and the DP bump topped out at 102 (5.7), a 31 (1.7) point surge. It’s incredible what insulin delivered in a timely way can do.