16 hr fast, aerobic v. resistance exercise and BG questions.

By Luis65 Latest Reply 2016-03-21 03:18:46 -0500
Started 2016-03-18 09:33:20 -0500

I've mentioned how limiting carbs, stress and cycling has allowed me to decrease my daily dose of Lantus about 40%. I am currently prescribed 1000 MG Metformin twice daily. I would like to decrease that to 500 MG twice daily. I have no desire to eliminate it or to increase the Lantus. I have reduced the Metformin to 750 MG twice daily and have experienced some BG instability. My log here stays green but I will have blues and orange giving an overall average that is in the green.

About fasting; If my morning BG is higher than my usual I forgo breakfast until noon. This was the case yesterday. Morning sugars have been running in >76 to <84. Yesterday it was 94 which is not high but I thought I would fast. After I did a fast 1 hr bike ride BG was 84. I ate at noon and 2 hrs later by BG dropped to 63.

This morning I woke up with 58. 2 hours later it was 151, 3.5 hours after eating and a 1 hour bike ride it was 94.

I know this is probably been too much information, but who else can I go to. OK my questions about fasting. I know that several of you are proponents of fasting and actually do a 24 hour fast on occasion with the idea that it reduces the stored sugars in the liver and so reduces morning sugar rise.

Is my timing of doing the 16 hour fast to slightly elevated morning sugars good thinking?

I have read here and other places about exercise causing a temporary rise in BG. I have not seen that in myself, but the opposite. I don't do regular resistance exercise as there is plenty of lifting on the farm.

Is a rise in BG connected to resistance exercise and not aerobic?

12 replies

Type1Lou 2016-03-18 18:36:50 -0500 Report

Luis, I can't speak to the fasting but have you checked out Gary Scheiner's book "Think Like a Pancreas"? He's an exercise physiologist as well as a diabetic and has some really good data and info on exercising with diabetes. He says "…aerobic exercises (performed at a sub-maximal level over a period of 20 minutes or more) will have a tendency to cause blood sugar levels to drop, due to enhanced insulin sensitivity and accelerated sugar metabolism." He also notes under Anaerobic Exercise and Competitive Sports that "it is not unusual to experience a blood sugar rise at the onset of high-intensity/short duration exercise and competitive sports. This is caused by a surge of adrenalin…"

Pegsy 2016-03-18 17:43:43 -0500 Report

Walking always lowers my glucose. Resistance training always raises it although not as high as it used to. That must mean my insulin resistance is improving. I always eat breakfast right away because it brings down my morning glucose very quickly. I take vinegar at bedtime and that has helped lower the dawn phenomenon numbers. Not as low as I would like (stress is high) but still much improvement.

Dan360 2016-03-18 13:55:40 -0500 Report

According to what I have learned from articles about diabetes and experienced from my own efforts the rise in BG after exercising is a function of insulin resistance. I.E., the greater the insulin resistance the more you will notice the rise in BG after exercise. If you exercise on a daily basis that will go away. While resistance exercising is the most effective at decreasing insulin resistance aerobic exercise also works. Just much slower.

Luis65 2016-03-18 14:43:21 -0500 Report

"the rise in BG after exercising is a function of insulin resistance"
That make me think I must not have a lot of insulin resistance left as I am not seeing a rise after exercise.

Dan360 2016-03-18 17:42:08 -0500 Report

Insulin resistance is controlled by exercise. There are two drugs Actos and Avandia that are supposed to work on insulin resistance but they are of questionable safety. While insulin resistance is held down by exercise if you stop exercising it will come back. Also, if you do heavy exercise such as weight lifting your liver may release glucose as part of the "fight or flight" response.

WASHED OUT 2016-03-18 17:14:52 -0500 Report

Liver dump of glucose or a fatty glucose transfer. Your brain sends out a chemical signal that causes your bodies storages to put more glucose into your system because you have just used a good amount doing your exercise. The body stores excess energy from periods of feast and resting, then uses it later when called on. If it can not get energy from your stomach contents then stored energy is called for.

Beckett 2016-03-18 13:16:26 -0500 Report

The body needs time to adjust to any change in your routine, so maybe continue to keep good record of what's happening and watch for patterns to develop.

Here's something — and everyone's different, I know — but when my morning BG was higher than I liked, eating breakfast SOONER than I normally did brought it down within the hour, normally down to the mid-eighties. I know one person in my personal life who has this same issue. She gets a pretty strong dawn effect, but can offset it with a LCHF breakfast. Not eating actually causes her to continue to slowly rise through the morning.

A 151 after a low of 58 might just be your body dumping glucose to offset the low. If your insulin response is compromised, you won't be able to compensate for the dump, hence the 151. Just a guess.

Moderate aerobic exercise lowers my BG. Strength training gives it a boost. But since the long term benefits of lifting weights is increased insulin sensitivity, it's worth the short term rise for me.

I hope this input is helpful.

Luis65 2016-03-18 13:36:09 -0500 Report

Thanks for the thoughtful reply, I would like to read more about the effects of aerobic and resistance on immediate and long BG. My ride this morning was not really moderate. I suppose I should get a heart monitor to let me know when I am going too hard. I am always trying to improve on my personal best. I guess I am competitive if only against myself. I love going fast.

I just did an upgrade on my road bike and it just zooms along- but I have got some definite muscle soreness. I take that as a good sign, pain in joints-BAD, pain in muscles - GOOD, as long as I can walk, hee hee.

GabbyPA 2016-03-18 09:49:28 -0500 Report

Pin pointing the cause of the rise is a daunting task. My aerobic is swimming laps and I have always done that on an empty stomach because it's 5:30 in the morning when I go. I always, even now after I have been fasting for a few months, will rise about 30 points. I go down later, but if I test right after my session, I am always up.

You say you are on limited carbs...do you know about how much? The reason I ask is that when you are geared to burn carbs for energy (and most of us are) then you are continually feeding the liver things to turn into glucose later. What you body may have been doing it giving you some help.

When I first started fasting, my numbers would climb the longer my fast went on. Sometimes as much as 100 points. But now, I have been doing it more regularly for several months, it doesn't do that anymore. It might be that your body needs an adjustment time to going without. My numbers are always best the first two or three days after my 24 hour fast. Go figure...I don't get it except that I might be increasing the sensitivity to insulin and I just have a long way to go.

When I first started fasting, I also was very careful with exercise. And when I fast 24 hours, I do not do any resistance training. I still do my daily stuff, but I don't go to the gym. I try to give my whole body a rest that day.

Luis65 2016-03-18 13:40:11 -0500 Report

Thank you as well, Gabby. I would like to say that the jump in BG this morning was not fasting. With a morning of 58 I ate promptly. Anyway I will keep up the good fight and track what is happening.

Since I retired I lost about 25 pounds, mostly in the midsection. I was hoping to lose another 10 but have plateaued out. I think the belly fat is melting away and that loss of weight is being replaced by muscle.