Welcome once again to our weekly advice column, where we talk all about navigating life with diabetes. In this edition of Ask D'Mine, our host Wil Dubois (veteran type 1, author and diabetes community educator) offers some wisdom about insulin's activity and a question on medical procedures that may not even be needed. Take a read and let us know what you think!

{Got your own questions? Email us at AskDMine@diabetesmine.com}


Lizzie, type 1 from Washington, DC, writes: I love your weekly column, it's the first thing I check on Saturday mornings.  As a show of gratitude, I've got a great question for you: What's the connection between exercise and the action of insulin on board?  If I inject a correction bolus and then exercise, I know the insulin will work faster but does that mean that it will also clear out of my system faster? One unit lowers me 50 points over 3 hours, but if I throw a run in there will I just drop the same 50 points, only quicker, or will I drop the 50 points and then even more because the insulin in still active in my system? In other words, is a little bitty insulin molecule like a bee — it stings a glucose molecule to get it into the cell, then its stinger falls off and it dies? If you can answer this, I'll love you forever!

Wil@Ask D'Mine answers: Lord knows I need all the love I can get right now, so I desperately want to be able to answer your question. The problem is, I don't know the answer. It seems logical that the insulin would get used up. I mean, there's only a finite amount of insulin in a correction. Once it gets used up, it's gone. Or it should be. And yet... from both what I see in my own body, and from what I see in patients I work with, it seems the insulin never quite goes away. So what's up with that?

To get to the bottom of this (and to earn your undying love) I turned to the clinical research journals to try and see what's known and not known about the life and times of insulin. It turns out there are a ton of studies on how exercise and insulin dance with each other. The problem is that most focus on type 2s, and the effects of insulin production and resistance in that population; and what you want to know is if injected insulin gets used up more quickly, or not.

So I had to go to Plan B. I asked some experts. A bunch of experts. And here's what the ones who responded told me...

Ãœber-CDE and author Gary Scheiner tells me that insulin "will start working sooner, peak earlier, and dissipate sooner" if it's injected near a muscle that will be active during exercise, and if the shot itself was taken within half an hour of exercising.

Donna Tomky, immediate past-president of the AADE is on the same page, saying "insulin absorption from an active muscle often provides faster action." Like Gary, she says this increase in speed will shorten the duration of action at the same time, and adds that this is true of longer-acting insulins, as well.

But not so fast, Superstar Endo Dr. Steve Edelman disagrees, stating: "the insulin will work faster with exercise, as it gets taken up quicker in the bloodstream, but it will not get out of your system faster."

Don't you just hate it when the experts can't agree?

On the bottom end of the world, Australia's diabetes and exercise guru, Coach Allan Bolton, sums it up best by saying: It depends. OK. I paraphrased the coach's thoughtful and detailed answer. What it depends on is the type, intensity, and length of the exercise. Like me, he searched the clinical research and found bupkis (my word, not his). So he pow-wowed with his endo and between them they decided that exercise "could possibly shorten insulin's action time." Their thinking wasn't limited to the insulin being used by the muscles; they also took into account the increase in circulation from exercise running more blood through the kidneys and liver, which "clear" excess insulin from the blood stream. Smart cookies, those Aussies.

But Coach Bolton also cautioned, "It would be remiss of me not to note there is a wide range of variability in insulin action time courses between individuals." Or as we say here in the states: Your Diabetes May Vary.

So I doubt that's a good enough answer to earn your love forever. You probably already knew your diabetes varied. But, as it is with many things in diabetes, this variability seems to be the only answer we have.

Sometimes the truth is, there is no truth.


Gary, type 1 from New Jersey, writes: I heard about this big campaign about "unnecessary medical testing." I'm sure there are plenty of doctors prescribing procedures that aren't really needed, but this kind of scares me for diabetics. What if our doctors start to push back on A1C tests, eye exams, kidney tests and all the other stuff diabetics are supposed to have regularly to stay healthy? What do I do if my doctor says "no" to a test I think I should be having?

Wil@Ask D'Mine answers: I'm guessing you're talking about the Choosing Wisely campaign. It's a joint initiative of most of the big doctors' organizations to reign in tests that aren't really needed, which by some estimates add up to as much as one-third of the healthcare costs in this country. A recent article in the New York Times points out that while previous attempts to reduce "unnecessary care" have failed, this one could succeed because it comes from "respected physician groups."

So what does this mean for us?

I doubt very much that this campaign will affect the kinds of diabetes screening tests you mentioned. First, Choosing Wisely is trying to curb things like CT scans for someone who has fainted. In other words, very high-end tests with minimal demonstrated need.

Second, routine diabetes tests aren't really at your doc's discretion. It's not like deciding what labs to run to investigate unusual symptoms. Diabetes tests are dictated by Standards of Care set down by doctors' professional organizations.

The standards, one from ADA and one from AACE/ACE, serve as blueprints for doctors that layout how diabetes should be treated. All the "stuff diabetics are supposed to have regularly to stay healthy" is spelled out in black and white in these documents (which run many, many pages and are assembled by the nation's top diabetes experts, based on clinical evidence).

For a doc to deviate from these standards would be tantamount to revolution, perhaps even malpractice. On top of that, insurance companies may actually penalize docs who skip tests laid out in the standards, and incentivize those who do. Why? Because diabetes is freakin' expensive for insurance companies and the standards lay out the expert-certified path to keeping PWDs in peak form. And insurance companies know that while that ain't cheap, it's heaps cheaper than unhealthy PWDs.

So I don't think you need to worry. But if God forbid your doc just says "no" to a test you think you need, ask him why he's not following the Standard of Care for treating your diabetes. If you get some runaround, get a new doc.

After all, it's a buyer's market!


This is not a medical advice column. We are PWDs freely and openly sharing the wisdom of our collected experiences — our been-there-done-that knowledge from the trenches. But we are not MDs, RNs, NPs, PAs, CDEs, or partridges in pear trees. Bottom line: we are only a small part of your total prescription. You still need the professional advice, treatment, and care of a licensed medical professional.

Disclaimer: Content created by the Diabetes Mine team. For more details click here.


This content is created for Diabetes Mine, a consumer health blog focused on the diabetes community. The content is not medically reviewed and doesn't adhere to Healthline's editorial guidelines. For more information about Healthline's partnership with Diabetes Mine, please click here.