Glucose numbers that trigger your attention

I’ve stated this idea many times here; please forgive my repetition. The simple exercise of more closely watching my diabetes numbers, both fingerstick and continuous glucose monitor, tends to improve those numbers going forward. The numbers trend toward better even before I put in place any conscious tactics to affect that improvement.

My guess for the cause behind this effect is that my subconscious mind gets to work on the situation and influences my diet, exercise, and sleep choices – all important drivers of blood glucose levels.

The brain is the best management tool

My brain is my most potent resource when it comes to glucose management. I’m aware that consciously adopting specific BG thresholds when I commit to stopping everything and devoting at least a few moments to take stock of my glucose metabolism and then come to some decided action consistently helps me manage.

Now I realize that diabetes is a complex situation where adding insulin, exercise, or food can all exert an immediate effect, yet also trigger subsequent down-line effects that must be taken into account before taking the initial action.

For instance, if you add insulin to bring down a high BG, you may moderate or even cancel that action due to personal experience during this time of day when adding insulin led to a subsequent hypo. Diabetes, like chess, requires you to think more than one move ahead.

I maintain in my head certain glucose thresholds that I’ve committed to taking deliberate action, including taking no action. I actually keep a gradient of levels both on the low and high side in my mind with varying levels of action, but for the sake of this discussion I’ll just use what I consider the most important lower and upper trigger points.

My low and high thresholds

On the low side, I regard 65 mg/dL (3.6 mmol/L) as a significant glucose level that requires a deliberate decision. This is the level where my body start to produce counter-regulatory hormones. Adrenaline, for example, triggers my heart to beat faster.

At 65, I take a look at how much of my last meal/snack is still in play as carbs on board (COB). I also look at my insulin on board (IOB) to see how much downward “push” this hypo trend is under. I definitely put off any plans I may have had to exercise. In addition to adding a glucose tab, I also consider temporarily raising my BG target from 83 to 100 (4.6 to 5.6).

The higher threshold that causes a similar commitment to action or inaction for me is at 100 mg/dL. Choosing this relatively lower “high” level is my overall commitment to keep my glucose primarily between 65 and 100 (3.6 and 5.6). I do relax this threshold after eating to the 120 level (6.7) for a few hours.

In summary, 65 mg/dL (3.6) on the low end and 100 mg/dL (5.6) on the high end are significant BG landmarks that cause me to pause, observe, and deliberately decide my next move, if any.

What specific blood glucose levels cause you to reassess?

Now I know that some people consider this level of attention to metabolic detail as an unnecessary interruption to the real business of life. I’m interested in your perspective, too.

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70 on the low side at least 2 hours after eating and 135 on the high side once there is no insulin on board (3.25 hours.)

At 6.5 my vision is already bleary.

Don, do you wear a CGM?

I love the trend graphs on my CGM. 78 is no big deal if it’s flat and steady. 78 is a big deal if I’m still on the way down. Same thing the other way. 135 is no big deal if flat or going down. 135 and going up I’m going to think about a correction or something.


I chose my target BG levels not by what they should be. I rather tried to pick the sweet spot between frustration and boredom. This puts my range at 55 - 120. My daily goal is to stay in this range at least 90% of the time. I use Clarity as my monitoring tool. In the last 90 days I achieved this goal 31 times. Everyday is a new challenge. I don’t mind it because sometimes I ‘win’.

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Looks like you’ve picked a goal that’s certainly achievable but requires good consistent effort, a “stretch goal,” perhaps.

Your reference to winning brings up the game dimension of what we all do. I think that this element of play makes the grind of the long haul tolerable for me – an antidote for the notorious burnout.

@Tim12 - The CGM and the graphs it can draw certainly help me keep my head in the game.

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Read what Tufte’s written about “Sparklines”. @Helmut a lot of superb data display design (Tufte-style) has gone into Clarity displays. Right click on a Clarity graph with Chrome (I think it works with other browsers too), do a “inspect”, and you can see the underlying SVG.

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I use G6, and have 75 as my low alarm, and 125 as my high alarm. These are the same values used by Ponder in his excellent book Sugar Surfing.

Your low number (65) is too low for me, because of the time delay inherent in CGM. By the time I hit 65 on the CGM I am already below that, and that is too late to turn the ship around if I want to avoid a more serious low.

I also think your high number (100) is too low for me, because I consider that a perfectly awesome number, and I wouldn’t treat at that level. Perhaps more important, setting too tight a range increases alarm fatigue. And certainly more important, the benefit of a lower than 5.0 A1c is not at all clear to me, thus neither worth the effort nor the extra time management and alarm aggravation.

That said, my average BG is usually around 100 (current 30 day average is 99.9 but usually a couple points higher), and std dev is less than 30. I’m comfortable with these results, using MDI Tresiba and humalog, and haven’t found the need to use a pump. Diagnosed as T1 in 1975 as a teenager.


Your approach makes sense. My interest in this post, however, was not about alarm settings but rather more of the numbers in your head that start you thinking about whether to take action or not. Maybe you leave that to the levels set by your alarms.

My high alarm, for instance, is set at 140 while crossing 100 going upward triggers my attention about what, if anything, I might do.

I am on the Medtronic Guardian CGM

oh I dare not mention my numbers, but if I am 120 I feel pretty good. Perhaps I am still too new to my type 1 (almost 2 months), but you all seem to have awesome control.