Possible delayed food absorption after insulin injection

Today I injected my insulin (pen injection) at the start of my lunch. This is my normal procedure when I eat. My BS at the start of the meal was 154 but it did not rise at all but instead began to slowly decrease. My BS always rises somewhat before going down. Over the next 2 hours my BS went slowly down and at 112 BS I had some juice but my BS continued to decrease slowly so when it went to 89 I took more juice and it turned around and started going up. Of course I over corrected and it went high. This type of incident (not showing ANY rise in BS initially ) has only happened once before (a couple of weeks ago).
My question is-was this a normal reaction (to have no raise in BS and only a slow decline) and nothing to be concerned about or does it indicate a problem with my food absorption?

Any thoughts would be much appreciated.


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Hi @edm welcome back. There are so many variables that my only comment is that it is difficult to say. I sometimes take mealtime insulin and drop as well but it is often when I have been dropping before a meal. Sometimes I drop immediately after meal insulin because of recent activity or exercise. I have to be honest, sometimes I take meal insulin and rise so fast it’s like I forgot to take insulin.

I’d say to watch it and see if you have a trend. If you start doing it more than a couple times a week it’s time to rule out your basal insulin and other stressors. My basal often needs adjustment as soon as the weather turns cooler. Cheers and good luck :four_leaf_clover:

A few possibilities come to mind:

  • One possibility is that on those occasions you ate at a time when your basal rate was higher - perhaps I should say peaking - which would mean you had more background insulin running in addition to what you took for your meal.
  • Fatty foods can slow down digestion of carbs and cause them to “hit” later, resulting in a delayed rise in glucose (on top of what you used to over-correct - which I’m famous for as well).
  • You might look into the glycemic index: aside from actual carb count, some foods cause BG to rise sharply, quickly; while others cause a more moderate rise which levels out.
  • Exercise can require some adjustments to your insulin, meals/snacks and perhaps carb ratio, perhaps lasting several hours or into the next day. It takes some experimentation to determine what to adjust, how much and when; and keep in mind that some people find certain exercises raise BG while others lower it🤪.
    Those are the first things I thought of and I’m sure Pruett forum members will have suggestions too. I wouldn’t get overly worried about for absorption just yet. Keep it in the back of your mind, talk with your doctor if it makes you more comfortable, and start with the process of eliminating.
    Keep us posted!

Hello Joe,

Thank you for your comments. Then mean a lot to me.

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Thank you for your ideas. I’ll check these out and get back to you.

I can very relate. Whenever my sibling is going to have her lunch her blood levels ALWAYS drop. And she doesn’t do any physical activity. If we don’t give her enough insulin at breakfast, by lunch her levels are super high. So we have to give her more insulin in the morning even if that means we are technically causing her a low at lunch. The frustrating part is that if we give her juice, then her bg goes up really high and she needs correction. So it’s a bit of a struggle but I think you’ll get used to it when it does happen. Good luck :four_leaf_clover:

Thanks for you comment Alexa

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Unfortunately I have suffered from the same issues you described in your question. As previously suggested I have slowly started to learn that my bolus timing has to be adjusted based on both activity and what foods were consumed. Pizza is one that will give me fits. All the fat significantly delays the rise in glucose and I have dived low only to skyrocket up when it finally hits. The one thing that I found helps me most is to keep a journal of times that I had issues, I keep track of activity pre meal values bolus values and timing.

Hello Jason,

Keeping a journal is a good idea. I’ll start doing that. Thanks!

Hi Ed, I agree with Joe & Wadawabbit. There are so many variables. Therefore I am only speaking to my experience. I’m wearing my 4th insulin pump in 16 years. After 1000s of injections I built up lots of scar tissue over 64 yrs of T1. My endocrinology PA-C knows about my varying absorption rate. Rather than change all my settings which would create more variables she suggests temporary incremental changes to basal & carb:insulin ratio or eat more carbs to prevent lows or treat the dropping bg before it gets too low. Her methods help keep me off the low-high bg rollercoaster. I too can overtreat lows or highs. She gives great guidance but I decided that being disciplined in controlling the variables I can is on me. Never beat yourself up when having problems with bg control. Pick yourself up & begin anew. Consult your Healthcare Provider. Mine is available although she is not in every day there is always someone who can help. Your provider may be able to help. When they get paid by insurance or you it’s not just for the office visit. It’s also for continuity of treatment.

I might suggest mapping where you inject on simple line drawing of the body & any unusual variations in bg for a while. I did this for cannula placement. I know the areas of my abdomen where insulin seems most effective. This really helped me in keeping my bg’s in my target area.

The method above is not foolproof. It’s only my experience. You see I have used a variety of tools for staying in my targeted bg range. I still contend with unexpected highs or lows from time to time. Best wishes in ironing out your highs & lows.


There are a number of excellent tracking apps available. I use Mynetdiary (I pay for an annual subscription); I think I’ve seen mysugar recommended here, and there are others which may be free.

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Hi, this may or may not apply but the liver plays a big part in our Blood Sugar, for example, have you ever had a high BS in the AM with out eating any thing, here is the reason, If you haven’t eaten your liver assumes you are starving and will deposit sugar in your blood, to stop it you need to eat first then take your insulin, but the liver also help s? digestion and sometimes it does it’s own thing so it may delay absorption depending on what the food is… Your blood sugar may be low and going lower when you eat so it may take a while for the level to rise because you may be lower than you think, you realize that our machines are about 80% of our true figure. Some foods take longer to digest, and if I want a quick rise, I’ll use apple juice, no need to digest just goes into the blood quickly. This is addl’ info, supposedly fat cells show up at an iinjection site, and this can delay the absorption of insulin.

Ughh, this has been happening to me lately and is super frustrating. :woman_facepalming:t2: Glad to know I’m not alone.