Delayed insulin absorption

Hi All,

I have been having a new issue over the past week or so. It seems that my insulin absorption is delayed significantly. Or maybe it’s something else…? Breakfast seems fine. At lunch and dinner, my blood sugar goes low three and four hours after I eat. The first and second hour it seems fine or slightly high. i am not using a GCM so not sure exactly what is going on. The only changes I have made is eating less fat. I still eat a fair amount, but was eating a higher fat diet previously. Not sure if that is connected or just a coincidence. I do NOT think it is a basal issue, as my BS in the morning is the same as when i went to bed. Any ideas?


Hi Jess the only way to rule out basal is if you successively skip meals, starting in range skip lunch and watch your blood sugar, then on a different day skip breakfast or dinner, etc. until you know what yout fasting blood sugar is for the whole day.

if your insulin absorption is delayed, everything else equal, your blood sugar would go very high stay high and then be at your starting point several hours after you eat.

If you are experiencing delayed stomach emptying, you might see it as a low blood sugar at +2 hours, this can also happen to me if I eat medium to high fats, it can delay the absorption of carbs and the insulin gets ahead of the sugar absorption - it appears like a low blood sugar after I eat… I guess you have to try to eliminate one thing at a time to have more information.

Hi @Jsich. In addition to testing basal rates, as @joe suggested, you might check in with
yoir nutritionist for some guidance on keeping things level with your new low fat regime.

Hi Joe,

Thanks for your response. So… the basal thing - if I “skip lunch”, does that mean I don’t eat lunch at all, or just delay it to see what happens? Also, there seems to be a HUGE difference in my morning readings and the rest of the day. I know this is typical, but listen to HOW much different: While I typically use a ratio of 1 unit insulin to 14-15 grams carbs, in the morning, it is about 1 unit of insulin to 6 grams of carbs. In addition, my insulin is often higher throughout the morning, even after I have breakfast. For example, this morning, I had 12 grams of carbs and 2 units. I then went for an HOUR long, very brisk walk. When I got back, my sugar hadn’t dropped at all, and was around 110. An hour later it was 130. So, it seems like it pops back UP in the morning, and is much steadier (or perhaps dropping) in the afternoon… Hope this isn’t TMI, I do appreciate your help!


yea @Jsich Jess, you completely skip the meal and the goal is to maintain blood sugar until the next meal (and then eat). that’s how you verify basal. Yes breakfast is the worst. If I eat my dawn phenom is way different than if I don’t eat. nothing is perfect perfect, but if you can get your fasting numbers really good, the rest is easier.

Every time the weather changes I have to tweak my basal. this year my overnight is off because I am low every single morning. I may have to dust off my CGM and wear it to figure out my overnight rate. I guess I can trial-and-error with a temporary basal overnight as well.

no. not TMI at all. with that much walking if I took my normal breakfast bolus I’d need an ambulance. I have a way more aggressive morning I:C, but I manually dial it back if I know I am going to be active, even walking counts.

funny-not funny: wife: “want to go for a walk” me: “no I just did my normal bolus and I’ll die” wife: “you’re not nice” (oh and this is the sanitized version in case children and sensitive adults are reading)

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If you’re going to test your basal rates I would definitely dust off the old CGM. The test is supposed to be suspended if blood sugar rises or falls more than 30 points, and you might not feel the difference, especially if the change is gradual.
You didn’t say how long you’ve been living with diabetes so forgive me if I’m telling you what you already know. But it’s not unusual to have at least a couple of basal rates throughout the day, abs the insulin/carb ratio could vary as well. Adding exercise into the mix is another consideration, but we learn by trial and error what works.
Be sure to check the guidelines for basal rate testing so your hard work isn’t wasted.

Hi Jess @Jsich, insulin absorption rate, and insulin ‘active’ duration a are two of the hardest things in diabetes management for me to figure out. And I believe that both of these bits can be clouded over by the overlap and interaction of basal and bolus insulin - and this has been true for me both when using injections and using a pump.

Theoretically, basal or background insulin should be able to maintain your blood sugar/body glucose level “In Range” around the clock without need for eating or for adding bolus insulin [I like @Joe’s thought on his dawn phenomenon] to bring you back in-line. using an insulin pump certainly makes this somewhat possible - I don’t think I could manage with background insulin, such as Lantus.

I will suggest, that the “fats” you eliminated from your diet might be the reason your BGL is going lower than formerly three or four hours after a meal. Intentionally or not, you may have included in your meal-time bolus some insulin to cover those fats, and now that bolus is your “delayed” action. This is something I went through unknowingly several years ago when my wife began preparing meals in a more “healthy” manner while keeping foods very tasty. The fewer “fat-carbs” sneakily removed from my diet over time lovingly influenced my to alter [lower] my diner-time carb ratios; now. if we ever get out to a restaurant again, I need to adjust for higher carb-count in meals I eat outside our home.

Thank you all for your thoughtful responses. Diabetes is really so challenging at times! There are just so many factors to consider, and it really seems impossible to control for everything (and to the men reading, just be thankful you don’t have a “cycle” - just one more thing to figure in). I am going to keep track of all my food, insulin, and timing for the next week or so and see what I can figure out. I was diagnosed about 2 1/2 years ago, at age 49, so still learning. I have read “Think Like a Pancreas” , “Bright Spots and Landmines”, which I found helpful. I also read Dr. Bernstein’s book (and another one on the same topic) on using a keto diet, and tried that for a couple weeks, which did NOT go well for me. I previously used a GCM, but became allergic to the adhesive, so stopped. In a way I prefer NOT having it, as I cold get compulsive about checking, and I HATE having something attached to my body (so, no pump for me). I so appreciate all the support and helpful advice I get from this website!

By the way, Joe, it occurred to me that you are the same Joe that gave me some advice about traveling with diabetes before my trip to the UK with my husband and kids last summer. You and others were so helpful, so thank you. I have to say, the best advice you gave me was to HAVE FUN. I know it sounds silly, but it is so easy for me to get wrapped up in this whole diabetes thing that I forget to enjoy life. And I did have fun! It was honestly the most amazing trip I have ever taken, and that was due, in part, to my being able to “let go” and just enjoy it. So thank you!


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Thanks for the update @Jsich. There are some great tracking apps of you don’t already have one. I use Mynetdiary myself. You have to pay for an annual subscription after a trial period but I find it well worth it, although there are others that are free. The more vigilant I am about using it, the better I tend to do.
BTW, I’ve never tried the keto diet but started eating Mediterranean style the beginning of the year, and it did wonders for me. My numbers were better and I think more predictable, and I lost weight! I recently got off track (cough cough) so I’m starting back up again.
You should probably let your doctor know about diet or food style choices, as sometimes that can help explain things that are going on. And your nutritionist can help you make sure you’re getting all the nutrients you need, even if you are following the guidelines of the plan. just thought I would mention that if you are checking out different ways of eating.

@Jsich I can’t thank you enough for the kind words and for telling me how that trip went. It warms my heart to hear this on a day where I really needed some good news!

Hi @joe. I’m sorry to hear you’re having a rough day, and I gather is just started. If it helps any I really appreciate the words of wisdom you share. Thinking of you. Take care

@wadawabbit, that’s so nice, thank you and likewise, I believe that input from a wide range of experience is the best kind of help we can provide.

not to hijack the thread, and I am willing to discuss on a new one, thank you for your thoughts… I try to not complain so much, but there can be times when this gets hard for any of us, no matter what background or level of experience. I’m stressed out I haven’t been taking care of myself, because of work. I am on a team of about 200 people working on a COVID vaccine. The pressure has been more than I have experienced in the 30 years I have been an engineer. My part of the design is dangerous and exposes people to risk (Im designing the freezers/cold chain for the whole factory) So I havent slept well and I havent been exercising. I threw away an entire afternoon design effort because I was 45 mg/dl and I cant trust anything I do when I’m low. I have to get my part operational in the next 4 weeks so we can get clinical materials ready. I even feel bad for saying it as I know there are many out of work, between the bulls*** of this virus and now getting a chance to actually do something directly about it… I put a world of weight on myself. and it makes blood sugar control harder and it makes me less able to tolerate the 25% of my day I reserve to taking care of type 1. I wish I didn’t have it this week. There. I said it.


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Hi Joe. I don’t mind continuing here. The thread is for supporting each other, both with advice/suggestions, and encouragement during trials, so thank you for opening up. I don’t want to keep you from your work so reply when you can, if you feel like it.
You’re working on a COVID vaccine - that’s HUGE (you can feel free to refer to me as “Captain Obvious” or “CO” from this point on :blush:). Thank you thank you thank you for your efforts!
You’ve been dealing with diabetes for a long time so I probably can’t tell you anything you don’t already know. But as a reminder, for the sake of encouragement, and because sometimes it helps to hear from someone objective, here are a few thoughts.
First, a little about me: I’m the older of two kids, and my sister has a developmental disability. So while she could do simple things to help out growing up, the lion’s share fell on me. And when our parents needed help as they got older everything feel on my shoulders. I’ve always been super independent and naturally handle things on my own - asking for help isn’t naturally wired into me. And I tend to take things on even if perhaps I should not. Obviously with work that may not be an option, but when it is, it’s important to remember - even say the words - “I can only do so much.” I know that’s easy to say as someone on the outside looking in, and I can’t begin to imagine what your work looks like and the amount of stress you’re under. But even with that, I hope you can find even a couple of areas where you can delegate some pieces, or where you can say “I’m putting this down for now and will pick it up tomorrow” to give yourself a bit of a respite. As you well know the best thing you can do - for yourself and your work - is take care of yourself, which must be incredibly difficult given the pressures of what you’re working on. Even so, I’ve found there can be areas where I can cut back or make adjustments if I look hard enough for them. And sometimes it can help to just take a few good, do breaths. Take a moment from your work; or before you get out of your car, while you’re on the elevator, at the water fountain… Sometimes that can help you can down.
I don’t know if any of that helps, and forgive me if I’m overstepping. I’m really grateful for you work, and when they come up with a vaccine we on the forum can say “I know somebody who worked on that!” I will be saying it with great pride and gratitude.

Hey Joe,
Just to add to what Dorie said, some advice my mother gave me (who is 84 and has lived through years of alcoholism- she is 40 years sober, three divorces and the suicide of one of her husbands). One day at a time, feel the fear and do it anyway, this, too, shall pass, and remember the serenity prayer (if you’re not familiar with it, look it up. I’m not a “religious” person, but it has gotten me through some tough times). I will be thinking of you.


Thank you @wadawabbit and @Jsich good stuff. I am usually pretty good at one day at a time but there are days when I am more like the bug than the windshield!

Dear Joe,
Thank you for your work. I empathize completely with what you said about when life becomes way more important and demanding than diabetes–and I’m not even working on a vaccine! My blood sugars probably bounce more than than most people using Tandem’s Control IQ, but they’re still better than Lantus and Humalog shots. Good luck!

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Hi there

It IS significant that u are now eating much lower fat. There is a direct connection between food absorption And fat.

Your insulin is likely working fine but u r used to bolusing for a higher fat meal. Fat combined w carbs cause BG to rise more slowly but can the remain elevated for 4+ hours. Many of us struggle to cover pizza and and yummy Mexican food fort hat reason.

Checking basal rates is good in general but your issue seems to me more likely related to blouses.

If you had a ratio, say 1 unit to 15 gm carbs for your higher fat meals, talk to ur endo/CDE about testing, say, 1:17 instead for a few meals.

If you r noticing a minimal “rise” in the 1-2 hours after eating (u need to test to find that out), then it’s most likely due to too much insulin now covering the carbs.

Hope u can follow the logic here.

Yes, I think I follow you. After paying attention to it for a few more days, and re-reading parts of “Think Like a Pancreas”, here is what I think was happening: The high fat not only delays the absorption of my meal, but also, 3-4 hours later, may have been keeping my BS steady because a high fat meal will increase triglycerides, causing the liver to release glucose. Yesterday I did try eating more carbs per 1 unit (16-17) when no fat was present (e.g. fruit), but I was still going low 3-4 hours after. So I reduced my basal dose from 5 to 4. I am guessing that will take a few days to take effect. I’ll see what happens. My only problem is that in the morning, as in, the whole morning, up until noon practically, I tend to have higher BS numbers. So my concern is that hours 2, 3, and 4 after breakfast are going to go way up due to my lowering my basal. Any suggestions?


Hi Jess
I really believe that the issue is your Bolus and not Basal (maybe u mid-typed below?).

Assuming we r on the same page and you bolused 4 instead of 5 units for the meal, then I would look at the timing of your bolus. The carbs in a no- or low fat meal will hit FAST and so we should take our insulin long enuf before that happens.

If u r somewhat more insulin resistant at breakfast time, consider taking your meal bolus 20+ minutes before ur first bite. Folks with a CGM can wait to see when their BG starts to head down and then eat. Assuming u r using Humalog or Novolog, it takes 20+ minutes to begin working when our BG is in normal range. It takes Longer to have an impact if we r high and less time if below 100.

You may want to use a lot more strips as u learn your pattern and then can test as usual. I’m not a medical professional so be sure to consider chatting with ur endo/CDE who likely knows a more complete health/meds picture.

Another tip is to exercise after meals if u r not too high (or low) to safely do so.

Does this help?

I don’t have a solution for you, but this happens to me also every morning. My morning shot doesn’t seem to start working for at least an hour so I have to inject 60 minutes before I eat my breakfast otherwise I go sky high. I have no idea why, but I’ve learned to just cope with it. Until I got a CGM I had no idea this was even happening. I would wake up, test in a fairly good range, eat breakfast, and test before lunch and I’d usually be in a good range again. When I got the CGM I was shocked to see what was happening after breakfast and before lunch!

Good luck!