Is there a BG point of diminishing returns?

What we are all seeking, I assume, is BGs in a range that does no long-term damage to our bodies. I realize that may be a little different for everyone, but with that goal in mind, is there a point of diminishing returns on the low end? Is 80 any better than 100? Is 70 better than 80? A CGM has made it much easier for me to stay at a lower level than fingersticks, but at some point does it become useless to try to be even lower?


I consider 83 mg/dl to be the perfect BG. But I consider anything from 65-99 mg/dl to be excellent, 100-120 mg/dl very good, and 121-140 mg/dl good. I will correct anything that is over 90, even though that is an excellent BG, I think I can make it better. I’ve made enough small corrections to know that they usually work and will not induce a ride on the gluco-coaster. In fact, these small nudge corrections are one of the highest percentage successful tactics that I use. For me, there is little risk in correcting an already acceptable BG. The corrections are often 0.1-0.5 units of insulin.

I do take into consideration the current trend, digestion status, the influence of exercise, and any pending insulin that is yet to act (IOB).


I’d do the same thing, though I wonder how accurate a 0.1u dose is. I don’t tend to correct anything below 100, at which point, I’d need 0.5u (or more), which seems to me a more likely-to-succeed (to do anything) dose than anything smaller. My current BG is 74 with 0.36u IOB - and I don’t expect to see anything change while that winds down. It’s great that such small doses are so reliably effective for you.

Terry and Thas have made some interesting suggestions on using small corrections to maintain better control, but they haven’t really answered your question. Studies show that the rate of complications decrease by about 20% for every 1 point drop of your A1c and other studies show that even with an A1c in the 5s someone with diabetes has a higher risk of complications than someone without diabetes.

There are diminishing returns at every level but the returns are still positive as long as you don’t either increase your risk of severe hypoglycemia to the extent that it outweighs the benefit of the lower risk of complications or you make yourself so unhappy with the efforts required to maintain better control that you’re suffering now rather than possibly suffering later.

A 70 is worse than an 80 and a 60 is worse than a 70. Terry’s 83 is the perfect number whether it is the perfect target depends on you and your situation.


I agree, @still_young_at_heart. My take on the relationship between overall blood sugar control and the risk of diabetes is this: we can only change the relative risk, not the absolute risk. But I take heart in that position. If I still come down with a diabetes complication, at least I can take comfort in the knowledge that I’ve done everything reasonably possible to better my odds. Life is risky.

So, to answer @Jim2’s direct question, I think as long as the downside of any correction can be kept to a minimum then I think minor corrections are worth it. That value judgment, of course, must be made by the person with diabetes.


After “doing everything reasonable” to avoid getting Type 2 diabetes and, losing that “odds battle,” I sure hope I can do better on the complications front!

Luck trumps skill. It’s life’s demonic insider joke!

But you must remember: Luck is dumb. Skill is not.

1 Like

There is certainly a point of diminishing returns, but I think trying to define it numerically misses the point…

If you have good control but are spending countless hours and frustration trying to achieve ‘perfect’ control (which is probably not attainable) you have likely surpassed this point of diminishing returns


The endo who prescribed my first pump liked to tell me to spend less time worrying about my A1C and more time living. She pointed out that it’s important to look at one’s health a bit more holistically. In my case, with virtually no complications (slight neuropathy in my feet, but unclear that it is related to diabetes), she had little concern with my mid-6 A1Cs.

My current endo has no concern with my post breakfast readings that seem high devoid of context, when I ultimately end up in range 3-4 hours post prandial.

So, I essentially agree with @Sam19.

I understand all the quality-of-life, it’s-not-all-about-the-numbers comments. But my question actually was about the numbers. Assuming you could do a pretty good job of keeping your BG at a steady 90, 80, 70 or even 65, what should your target be, and at what point does a lower number provide very little or no additional benefit in terms of helping protect your overall health?

It’s widely debated Jim and experts are all over the board on the subject… There seems to be little overall agreement over which levels are healthy or even which levels are normal…

1 Like

Thanks, @Sam19

I think that it’s somewhat backward to define success as a BG level, get there and rest on our laurels.

Flow by Mihaly Csikszentmihalyi lays out a theory of engagement and enjoyment that I think works very well with diabetes. It doesn’t matter if we have a study that shows an average BG of say 95 is “better” (or “worse”, of course, since we hear stories of many folks having achieved lower BG being told “your A1C is too low…”) than an average BG of 140. If you are working to succeed with diabetes, and I’d say there are many different and legitimate definitions of success, we can use notions of improvement to help us work to maintain the focus, which will feed our desire to succeed and create a closed-loop of positivity that I have found alleviates some of the negative sensations that diabetes has been found to cause.


I’m not trying to claim any kind of “success,” and I’m not really sure why some folks seem to be bothered by the question. It’s strictly theoretical: is there a level at which it makes no sense to try to go lower? Do I microbolus at 85 to try to get to 75, or is that just senseless?

Probably senseless, I’d say if your bg is below 100 (before meals) there’s no rational sense in chasing it around any further if you’re looking for a line in the sand

I don’t think there’s any research on this issue either way, which leaves it up to personal choice and opinion, hence the direction of the discussion.

That is both senseless and perhaps dangerous. If you were to achieve the impossible and maintain a steady 85 +/- 15, you would have achieved normal blood sugars for a person with a fully functional pancreas. A 75 isn’t more normal and shooting the extra insulin does hold some risk of ending up low.

this website has a lot of information on reducing A1c and health.

I’m familiar with it… The proprietor of the website is a member here, but hasn’t been active lately