Unexplained insulin sensitivity decrease?

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Anyone have a time when their insulin sensitivity decreased dramatically? Any thoughts or ideas on a cause? It’s happening to me and I’m so frustrated!!!

I’ve been T1D going on 27 years and am very well controlled. My A1C has always been in the 5 range. A couple months ago, my sugars starting rising and I can’t figure out why. I’m spiking much higher than normal from everything I eat, my pump setting for corrections of highs is working at about half what is has in the past (I’ve been on a pump for almost 14 years so that’s not a new thing for me), my night sugars are dropping significantly slower than usual (I’m on a Dexcom CGM sensor as well), and my last A1C, earlier this week, was 6.5. I haven’t been that high in as long as I can remember. I know it’s not significantly high, but it’s high for me.

Nothing in my day-to-day life has changed…I’m eating the same, exercising the same, not stressed (except about this now), etc. I seem to have spurts when I’ll be a little less controlled for 2-3 weeks every so often, but this has been going on now since mid October and isn’t working itself out.

I just saw my endocrinologist and she thinks it’s odd too but didn’t have any suggestions for why. We’ve adjusted my basal rate for most of the day but that was just yesterday so I don’t know whether that will fix the problem or not. But regardless I’d like to know the cause rather than just make an adjustment while it keeps happening.

I’d love to hear if any of you have dealt with anything similar. When I look for information on insulin sensitivity changes I’m only finding suggestions for ways to increase it. I need help figuring out why it’s decreasing. There isn’t anything obvious so I hoping someone out there has an idea. Please share!

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That happened to me in the 1990s, and I also gained weight. That was when I switched from animal insulin, to synthetic insulin. My doctor diagnosed insulin resistance (IR), which can happen to type 1 diabetics. IR is a type 2 characteristic, but many T1D’s have it too. I am not saying that you have IR, but it is a possibility. I started using Metformin. After 18 months I had lost all the extra weight, and stopped the Metformin for more than a year. Recently I started gaining weight again, and resumed taking Metformin. I also cut my daily carb count to 130 carbs per day. Now that my weight is much better, I am eating 160 carbs per day, and I am 6 pounds overweight.

Another possibility is having scar tissue, which causes poor absorption of the insulin. That requires an increase in insulin usage. Changing sites for your infusion set, or injections, should be done if there is scar tissue.

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hi @jwells73 this happens to me up to 1x per year. in my opinion it can be from reduced stress in your life, it can be from a new exercise program (exercise benefits can last up to 3 days) or… it could be from insulin production. once in a while i think i actually make insulin again because my decreased sensitivity lasts for 2 sometimes 3 weeks. It’s nice to have a second (third…fourth) honeymoon once in a while.

ease up on the insulin and test more. =) you’ll be okay. there’s a 1:1,000,000 chance it could be of concern so if your sensitivity gets crazy please check-in again with your endo.

hi @RichardV, hope you are well.

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Hi @jwells73,

The simple “why” and I do not to make little of this is that your body is changing and [maybe] the weather is getting cooler; I always need more insulin in cooler temperatures. Just recently I had to lower my sensitivity rates [now taking more correction insulin] by 20 points - did the lowering in steps. I’ve gone through the changes in sensitivity many times.

I would suggest that you validate your basal rates by fasting from all food intake for 18 hour periods for a couple of successive days when you do not plan on engaging in any unusual activity. A couple of times a year, at change of season, I will eat a normal dinner and then not eat again until dinnertime the next day, and then do this a second day. Then I’ll switch and just eat breakfast and lunch for a few days. After two days, I make basal changes on my pump and resume normal eating and then try to go long periods working solely on basal, with regular exercise which for me includes walking at least 4 miles each day.

The above procedure works well and is safe when insulin needs are increasing but show extra care and break your fast anytime your BG is falling. During the periods when my insulin need increases, I don’t hesitate to give correction bolus and use this data, prorated, when making pump basal changes.

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Part of the problem with searching for more information about what is happening is the terminology you are using to describe it.

Referring to it as a decrease of your insulin sensitivity (factor) is, of course, very technically correct. But the “insulin sensitivity factor” is frankly one of the most confusing values to work with in MDI or pump therapy. The fact that a lower number implies you require more insulin to lower your BG (Blood Glucose) by a given amount is never obvious for me.

The language I am more used to seeing in this context is an increased resistance to insulin or simply “insulin resistance” as was already mentioned in an earlier post. Of course, it might actually be the result of something else. But insulin resistance seems like the most likely first assumption to perhaps investigate further.

When you talked this over with your endocrinologist, what terminology did she use to refer to it? Did she bring up any of the drugs which are supposed to help reduce insulin resistance during your conversation?

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She did talk a little about insulin resistance but more along the lines of whether I was having problems with my sites or any signs that would make her think I was dealing with scar tissue. She didn’t seem to think that was the problem. She didn’t mention any other drugs to help but maybe that’s the next step?!?

I know what you’re saying about my wording, so I’ll check with some other phrases.

But here is a “for instance” for all of you: my insulin to carb ratio is high: 25:1 and my correction rate is 1 unit for 80 points. I tend to drop fairly low at night, so I’m supposed to have my blood sugars at 160 before bed so I don’t go too low. I’ve had my most recent CGM for just 3-4 months and after the first week had to lower my alarm at night to 60 because I wasn’t getting any sleep. I drop to 70 or so pretty regularly.

The last two months I’m waking up closer to 120 (again, I know that isn’t horrible, but it’s not normal for me). When I calibrate before bed if I’m near 100 I’ll have what is my normal carb snack and instead of rising to 160 I’m shooting up to 250. I realize that’s why I’m waking up higher as well, but I don’t know why I’m jumping so high in the first place. I’ve had two instances in the last week when I was about 120, ate a 30 carb snack and once shot to 265, the other 310, within an hour. Weird!

Another time I woke up during the night and was at 140, so I bolused .5 unit thinking that should bring me closer to 100 and instead, 2 hours later had only dropped to 120.

So while I realize insulin resistance is maybe better wording, it’s not just the problems I’m having with insulin at meals, it’s also that I’m reacting to foods differently than I have in the past. That’s why I was asking from an insulin sensitivity phrase. But I guess that’s not it entirely either.

So with some added information, I’d still love to hear what words of wisdom you all have to share :). Thanks for what you’ve said already! It always helps to know it’s not just me.

Oh, and in response to the comment about change in the seasons…that is happening, but I’ve lived in the same place for 8 years and never had this happen, so it seems odd that suddenly things have changed now when they never have in the past. Maybe I’m just getting old, ha!

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When I calibrate before bed if I’m near 100 I’ll have what is my normal carb snack and instead of rising to 160 I’m shooting up to 250.
Well, actually that would also be expected, wouldn't it? If you need more insulin to lower your BG then you would also need more insulin to compensate for the carbs you eat, wouldn't you? Wouldn't your carb ratio also drop because 1 unit of insulin would no longer be able to cope with as many grams of carb as it did in the past?

I think someone has already suggested this, but, if you haven’t already, perhaps try to see how well your current basal dose still works for you. Since you have a CGM (is it a Dexcom?), then you just have to find a period when you have not eaten for at least 4 but better 5 to 6 hours and then see what trend your BG follows. It should be flat if your basal is dosed properly, right?

I tend to drop fairly low at night, so I’m supposed to have my blood sugars at 160 before bed so I don’t go too low.
That makes me guess that you are probably using MDI (Multiple Daily Injections) with a fast acting insulin for meals coupled with a basal insulin such as Lantus or Levemir. If you were using a pump you would simply lower your basal rates at night to avoid going low during the night.
Another time I woke up during the night and was at 140, so I bolused .5 unit thinking that should bring me closer to 100 and instead, 2 hours later had only dropped to 120.
Just a nudge here to remind you that the insulin from a bolus will be "active" for probably at least 4 to maybe 5 hours after you administered it. Of course, the "duration of insulin action" (DIA) varies from person to person. It is not one of the things people typically test and often they just assume it is 4 hours. I think mine is more like 4 1/2 hours, but my pump only lets me choose 4 or 5 hours. Annoying.

Opinions seem to vary as to what makes a good guess for DIA most folks. The article below is more conservative and thus should probably be taken with a grain of salt. Still, chances are most people tend to underestimate their DIA. Best thing is to just watch and see what happens, I guess. But somehow I find that hard to do.
An Accurate DIA Prevents Excessive Insulin Stacking

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Yes!! It drives me crazy. I’m still only around 3 years in, so I attribute it to continued pancreas death. Usually what happens is I have a really bad cold for two weeks (which obviously reduces insulin sensitivity due to sickness) but afterwards my insulin needs remain elevated permanently, and I need a much higher basal and bolus than before. Always takes me a long time to believe it. Happens maybe once every 3-6 months, and throws my bg management into chaos every time. :frowning: