GCM installed: trial period

[mccoy]

Hi guys, I just received the freestyle libre GCM sensor which I installed on my arm. It's from abbot and every nation has its official site.

Pros: reasonable price, free trial sensor in some areas, duration of sensor 14 days, convenient to wear.

Cons: unlike the Dexcom GCM, it needs to be scanned every time a reading is desired.

I started monitoring glucose concentration just before dinner: 89 mg/dL. Now I'm having lowcarb dinners, according to the observations that glucose tolerance follow a circadian rythm.

After a while (50-60 minutes) glucose peaked at 122, then quickly down to 104 after 110 minutes. I wonder what caused that peak since there were very little carbs in the meal (spinach and cherry tomatoes, nonfat cottage cheese 150 gr, nuts and seeds 60 grams. 

The trend is consistent with a limited error. Data do not fluctuate wildly. I'm going to see when the values reach the background again and what the fasting value is going to be tomorrow.

Then the behaviour in the presence of carbs, in the morning and after lunch.

 

[Todd Allen]

4 hours ago, mccoy said:

After a while (50-60 minutes) glucose peaked at 122, then quickly down to 104 after 110 minutes.

To minimize post prandial blood glucose you might try going for a walk after a meal.  I can eat up to about 50g of low glycemic carbs without a significant rise in blood sugar if I promptly take a 30+ minute walk.  Weightlifting does the opposite and can pop my blood sugar up to 120-130 unless I'm deeply fasted.

[mccoy]

Todd, thanks for reminding me, unfortunately there isn't always enough time for postprandial mild exercise.

Do you wear a GCM? The detail of the glucose response to meals, exercise, and other factors is surprising for those who are not accustomed to such a device.

For example, the suddenness of the first peak, even with complex carbs, theoretically long-to-digest like whole grain pasta. The income of successive peaks, of unknown origin.

I hit 165 mg/dL for a couple of minutes today just after eating 100 grams of pasta with vegetables.1 hour after the meal the values went back to baseline, to rise again 2 hours after at 133 mg/dL. and now they are trending downward. I just washed my car in the meanwhile...

By fingerpricks, this kind of detail is impossible to achieve.

Edited July 2, 2021 by mccoy

[mccoy]

So far, the most important observation to me is that I have a high baseline of blood glucose concentration, hovering around 100 mg/dL. I woke up with it, it tends to hit that value again after peaks. Of course, it's too soon to draw any conclusion, but I spotted this high fasting glucose baseline for a few months and the GCM is but confirming it. 

[Todd Allen]

26 minutes ago, mccoy said:

Do you wear a GCM?

No, I've only done conventional finger prick testing.  I started tracking my BG about 5 years ago when I realized my muscle wasting disease is a predisposition to poor glycemic control.  The extreme nature of my issue was apparent without a CGM.  I probably went a bit overboard having bought 5 different meters and a few thousand strips but I was slow to understand and accept my limitations.  A year and a half ago I found megadosing vitamin C very helpful after learning I had lead poisoning but vitamin C interferes with all of my blood gucose meters.  I stopped tracking BG to manage carbohydrate consumption and to keep stable blood sugar I cut most of the vegetables, fruit, nuts and seeds from what had been my fairly relaxed keto diet.  Other than further rise in LDL and sex hormones in every other way I've experienced ongoing improvement in health, fitness and physique.  Much of my improvement may be due to dropping my blood lead from 45 mcg/dl to 5 mcg/dl but I've adjusted to this new dietary pattern and expect to stick with it as long as it seems to work well for me.  If I regain desire to consume carbohydrates I could see value in a CGM but for now the cost benefit ratio looks dubious.

[mccoy]

5 hours ago, Todd Allen said:

I could see value in a CGM but for now the cost benefit ratio looks dubious.

The Libre is not so costly though. Maybe more so in America. There are even ways to extend its life, although I don't know if the reliability is compromised.

Strangely, my blood glucose went down below 90 in the evening, less than when waking up. At dinner I had a lowcarb meal and a negligible glucose peak. 

The dinner strategy is pretty easy to implement, although it may take time to yield results.

Sequential measurements seem to show that the error is not an issue. Maybe the device uses some error correcting or interpolating algorithms.

[BrianA]

It would be interesting just to try a walk after eating the exact same meal that caused a spike, and see what happens. If it helps, you can consider then getting a slow walking-speed treadmill, I use one at my sit/stand/walk desk after breakfast and lunch while doing work on my computer.

[Dean Pomerleau]

9 hours ago, BrianA said:

It would be interesting just to try a walk after eating the exact same meal that caused a spike, and see what happens. .

I agree it would be interesting. See this thread (by Mccoy) :

The last study discussed in that thread seems to show that low intensity, long duration exercise (walking) after a meal effectively blunts the spike in glucose and reduces the area under the curve. 

--Dean 

[mccoy]

Yes, the main difficulties in those glucose blunting schemes being that it takes time and planning, not always feasible before retirement, especially so if increased-duration is chosen (which also seems to be more effective strategy).

[mccoy]

This is today's report, I only paste a small part of it because the forum software warns me about a threshold. I'll ask this in the dedicated thread.

 

• First measurements were at 6:45 AM, average 97 mg/dL
• The first small peak, at about 8:30 AM max 122-127 mg/dL (higher measurements), was caused by resistance exercise, bench pressing, and cacao with very little honey. Apparently, the system reacted to the inception of exercise by preparing to the job with some glucose secretion from the liver.
• The second large peak, at about 9:20 AM was surely caused by the ingestion of 2 ripe kiwifruit, very sweet. The highest point has a value of 178 mg/dL. The duration was brief but the value too high for longevity purposes.
• I stopped exercising at 9:30, in the middle of a downward rebound, with a minimum of 87 mg/dl just before 10 AM
• At 9:30, just after exercise, I ate a large quantity of nonfat yogurt, about 750 grams, with stevia and little honey. This caused the subsequent rise, no pronounced peaks but longer in duration with a max of 121 mg/dL. Then an undulating signal with a downward trend, 99 mg/dL at 1:10 PM.

The data collected by the smartphone can be downloaded to a PC app, which is pretty convenient to examine. Small circles are acquired data, which are interpolated unto a continuous curve as visible in the above graph.

Lesson from this morning: even if the morning is more favorable to eating carbs, do not eat more than one ripe kiwifruit. Also, do not eat too much yogurt, it contains 5 % lactose.

 

 

 

[Ron Put]

mccoy, I don't think that any of the CGMs are available without prescription in the US, and the requirements for the approved Freestyle CGMs are considerably more stringent in terms of warm-up and length of use (10 days vs 14 in the EU). The accuracy is supposed to be a little better in the US.

I'll be ornery and continue to question the accuracy of these things, especially since the Freestyle is considered the least accurate. I am assuming that you are using the Freestyle 2, instead of the original version, which is even less accurate.

See, for example, the comments from real-world diabetics here, which show enough inaccuracies to place the whole peak and trove tracking in some doubt. This is just the most recent one:

"

Elaine Lauer May 15, 2021 at 6:19 am - Reply

My mother in laws number was 60 on the libre and 200 with the finger prick test on her accu check… explain that? Scared me half to death. This is not the first time there have been very low numbers, now we know enough to check it the old fashioned way.
I made her eat peanut butter toast and drink milk to try to raise the numbers before. Now I think I know the problem. It is your Libre system

 

[mccoy]

On 7/3/2021 at 2:51 PM, Ron Put said:

mccoy, I don't think that any of the CGMs are available without prescription in the US, and the requirements for the approved Freestyle CGMs are considerably more stringent in terms of warm-up and length of use (10 days vs 14 in the EU). The accuracy is supposed to be a little better in the US.

Too bad, 10 days sounds a little restricted, unless people like to hack thedevice.

On 7/3/2021 at 2:51 PM, Ron Put said:

'll be ornery and continue to question the accuracy of these things, especially since the Freestyle is considered the least accurate. I am assuming that you are using the Freestyle 2, instead of the original version, which is even less accurate.

See, for example, the comments from real-world diabetics here, which show enough inaccuracies to place the whole peak and trove tracking in some doubt. This is just the most recent one:

Ron, the very bad review is most likely related to a faulty sensor, which the manufacturer is supposed to replace.

Accuracy seems not to be such an issue with my sensor, apparently the less recent freestyle. Once you know the mechanism of glucose homeostasis, you can foresee and interpret peaks, suspicious peaks may be spurious values or derived from unknown causes and can be checked by a traditional glucometer. In my 4-days experience, the peaks almost every time follow the expected mechanisms and vary according to foods and their quantity. You can readily spot the anomalous values, which do not follow a trend.

I don't want to speak too early, but the GCM seems a really powerful tool to keep blood glucose within the desired limits.

 

[mccoy]

The best aspect of wearing a GCM is that it induces powerful behavioral feedback. It opens a window into the world of glucose homeostasis how it's carried out by your individual system. I'm eating much fewer carbs now when I can see real-time their effects on blood glucose concentration. I also have an idea of why my fasting BG drifted upward and how I can adjust it downward. My only concern is how to do it and not to lose muscle mass.

Edited July 5, 2021 by mccoy

[Todd Allen]

3 minutes ago, mccoy said:

I also have an idea of why my fasting BG drifted upward and how I can adjust it downward. My only concern is how to do it and not to lose muscle mass.

Although I know strength training spikes my BG even when fasted I think it results in healthier muscles and better BG over all.  I used to have to keep my dietary protein moderate or my fasting blood glucose would rise back into the prediabetic range despite restricting carbs but now protein seems to have little to no effect on my BG.

[mccoy]

Todd, as you know apparently there is a duality to exercise: if subjectively strenuos, it will elevate BG. If subjectively moderate, it will decrease it.

It is easy to presume that in your fasted state glycogen is degraded and mobilized as glucose by the liver, after the effect of cortisol and epinephrine and glucagon.

Protein: I remember the case of the carnivorous Shawn Baker who, despite his zaero-carbs diet, displayed a 125 mg/dL fastign glucose. Strange but true.

[Todd Allen]

25 minutes ago, mccoy said:

Protein: I remember the case of the carnivorous Shawn Baker who, despite his zaero-carbs diet, displayed a 125 mg/dL fastign glucose. Strange but true.

He later reported that he was only doing extremely high intensity strength training, basically all anaerobic, on a rowing machine.  He switched to doing some aerobic level training before and after his strength sessions and with no change in diet dropped his fasting BG to 80 mg/dL.

[mccoy]

11 hours ago, Todd Allen said:

He switched to doing some aerobic level training before and after his strength sessions and with no change in diet dropped his fasting BG to 80 mg/dL.

Thanks for the update, that aspect always baffled me, someone must have given to him the right tip!

[mccoy]

Today I checked the baseline value with the strip glucometer, which read a 7 mg/dL lower value. Checking the baseline is a good way to check for systematic errors.

My baseline still hovers around 100 or higher mg/dL, it will take some time to lower it. I had interesting graphs to show, but the forum programs doesn't allow me to post them.

 

 

Edited July 7, 2021 by mccoy

[mccoy]

Experimentation with the GCM sure yields interesting or very surprising results.

First of all, I tested it today for the second time against an accucheck viva glucometer. 107 g/dL the libre reading, 104 the accuchek reading, with a negligible error.

 

Edited July 11, 2021 by mccoy

[mccoy]

Below is my daily BG as acquired by the Freestyle Libre sensor. At night and in the early morning it hovers around 100, 105 mg/dL. This night I had to wake up at 3:30 AM so I had a chance to do nightly readings.

The first little hump at hours 6:AM, with neglible deviations from the baseline (112, 111, 113 mg/dL) is a cup of plain soymilk. Low-carb item, response as foreseeable.

The big spike at 9:00 AM is 2 ripe kiwifruit (200 grams in total), eaten alone, no exercise after. It almost reached 200 mg/dL, maybe more since I took a 30 minutes nap after the meal.

At 12 I hate plain nonfat yogurt with ground flaxseed and chia. Very moderate response. Then I ate a large slice, about 300 or 350 grams of millefoglie cake, a birthday cake made in Italy, which was delicious but rich in fats and carbs. The response was so moderate relative to the carbs load that it really surprised me. The response is underlined in the orange circle. 126 to 133 mg/dL, with a 144 spike. But it was a monster load of carbs (although not too sugary), compared to the way healthier kiwifruit. At night I ate a huge dish of cooked vegetables with 100 gm of wholefat buffalo mozzarella cheese (I was on the road).  The response was very modest, as expected after a lowcarb meal.

My main takehome lesson is that a pure fruitarian meal in the morning with no subsequent exercise is not such a healthy thing to do to those who are on the threshold of a prediabetic condition like me. Or those who want to optimize BG.

Whereas, as I verified today, fruit mixed with yogurt is far less detrimental to the BG signal.

 

Edited July 11, 2021 by mccoy

[Dean Pomerleau]

1 hour ago, mccoy said:

The big spike at 9:00 AM is 2 ripe kiwifruit (200 grams in total), eaten alone, no exercise after. It almost reached 200 mg/dL, maybe more since I took a 30 minutes nap after the meal

I know this may seem like a crazy idea, but how about taking a walk rather than napping after you eat? 

--Dean 

[mccoy]

2 hours ago, Dean Pomerleau said:

I know this may seem like a crazy idea, but how about taking a walk rather than napping after you eat? 

LOL, the nap was mandatory since I had to drive long distance and I also happened to be forced to wake up at 3:30 AM. What I do usually is to have a treadmill workout just after kiwifruit, and that will blunt a little the spike. Due to work requirements, I cannot always do that unfortunately, if I were retired, I'd walk hours a day since I love that.

Today what I did is to eat a single kiwifruit, the last one of the stock I had. I ate it after eating 270 grams of nonfat greek yogurt and after a 20 minutes moderate treadmill workout. This is the resulting graph. It was a single kiwi so not a direct comparison, but the spike didn't even reach the 130 value. It would have been maybe lower if I had eaten wholefat yogurt, but that is not cholesterol friendly.

https://imgur.com/hIdnXmg

Edited July 11, 2021 by mccoy

[mccoy]

By teh way,k I don't know what's happening with the images. First, I cannot paste directly from a snapshot. Secondly, I tried to embed with an HTML code from the imgur sharing site. Successfully first time, not so the second time around. Such a drawback impairs the usefulness of this forum significantly

[Dean Pomerleau]

1 minute ago, mccoy said:

LOL, the nap was mandatory since I had to drive long distance and I also happened to be forced to wake up at 3:30 AM.

I suggest napping and then eating rather than the other way around. 

2 minutes ago, mccoy said:

Today what I did is to eat a single kiwifruit, the last one of the stock I had. I ate it after eating 270 grams of nonfat greek yogurt and after a 20 minutes moderate treadmill workout.

Sure, the yogurt will spike your insulin and thereby blunt the glucose rise. Whether that is healthier is uncertain. 

--Dean 

[mccoy]

3 minutes ago, Dean Pomerleau said:

Sure, the yogurt will spike your insulin and thereby blunt the glucose rise. Whether that is healthier is uncertain. 

Greek yogurt, with less insulinogenic whey=leucine, is supposed to stimulate less insulin than traditional yogurt. But yours is a reasonable hypothesis. We cannot  know in detail though, until some continuous insulin meter is invented. I hope soon.

I don't know if soy is less insulinogenic, but soy yogurt here is either sweetened and very costly.