Do you inject after eating to correct high bs?

I’m only in my first week of using insulin, so bear with me. It has been a roller coaster. I didn’t get very good or clear cut instructions from my pcp, just directions on how much insulin to take before each meal. She started me on a very low dose because I don’t generally eat carb laden things (I’m still pretty carb-shy because prior to finding out I’m type 1 everyone said I was type 2, so I was sticking to a Keto diet to address it, and now I’m stuggling to not fear carbs haha). So until I see her again I’ve talked to a family member who is a diabetes counselor. She warned me against injecting after eating to correct high blood sugar, which is happening because now I AM starting to include more carbs in meals. I don’t know what the “formula” is for how much insulin to use per serving of carbs. I understand it is different for everyone?

So, I’m wondering if I need to just let my blood sugar be high (doesn’t usually pass 300 but it can get close, like 260) until I eat next and then inject more to address it? Or should I inject in between meals to bring it down? Drink more water?.. I don’t know :frowning: What does it really mean to have high bs? Am I injuring my body if I let it be higg for a few hours?

I was instructed to test 2 hr after eating - having been informed that there is “insulin on board” for at least 4 hours after injection- to get the most accurate reading. Then based on that number, if it’s low have a snack because insulin will continue to lower it, or if it’s high… I don’t know. Check at 4 hr marker and see where it is and if it’s still too high, then what?

Hi Ariana @jimjamz, welcome to our world of living with diabetes and a warm welcome to this wonderful TypeOneNation site where you will find people just like you and many suggestions that will help you long the way to a bright and healthy life. Some information you receive will work well for you and other bits may not - each of us is somewhat unique.

You have asked many questions and said lots so I’ll start with, what in my opinion, are two important things to keep in mind:

  • Do NOT inject more insulin after eating [at this stage in your learning] and Never take a second dose of rapid-acting insulin, such as Humalog or Novolog, until at least four [4] hours after your first dose unless you are eating again. You want to avoid “stacking insulin”.
  • Do not be afraid of carbohydrates; your body, especially your brain, needs carbs. You will learn how to balance “normal” amounts of carbohydrate with activity and insulin.

200+ mg/dl Blood Glucose [BG] 2 hours after eating a meal is not “bad” and, unless your BG stays that high and higher all the time, will not hurt you. With time, you will learn to adjust your meal-time bolus amounts based on the content your your meal and on your pre-meal BG reading. That may sound complicated but it really is not difficult and will become second nature to you.
For me, and I began using insulin 62 years ago, I never have “good” or “bad” BG readings - what I have instead ar readings “in range” or “out of range”. Your BG readings are markers telling you that you are managing well or if you may need to make adjustments in your carbohydrate counting or in your carbohydrate to insulin ration for that time of day.
There is much, much more I could add here but I think I’ll stop here and invite you to continue this conversation here of by using the IM function - I expect many more people to add thoughts.
You will do well, Ariana.

Thank you so much, @Dennis. I greatly appreciate your response. The last day or so I’ve felt like I’m finally getting the hang of this, kind of. I will probably end up lulling myself into a false sense of security. I wasn’t aware of the 4 hour rule for insulin until after the weekend. I would inject and then eat, and then an hour later I would exercise and find out I was slightly below 60 when I was done. Kind of scary. Is there a rule of thumb for the amount of insulin one uses if exercising that day? Eat more carbs, or inject less? Thank you again :slight_smile:

Hi Arianna, I’m not as proficient at all of this as others who may respond to you. I am almost 7 months newly diagnosed. All of the things you described happened to me during my first couple of months though. It does get easier. I never exercise when I have active insulin in my body unless it’s going to Hgh and I’m trying to lower it. I asked my endo If was it was OK to just exercise instead of injecting more insulin and she said absolutely. But keep an eye on it so it doesn’t go too low. I have a CGM now and it’s extremely helpful, it’s test your Blood glucose every five minutes. Try to exercise before a meal. I’ve heard from many others on this forum that weightlifting and exercise of that nature, (anaerobic) May raise your blood glucose while aerobic exercise like walking and calisthenics lowers your BG. Hope this is helpful. Good luck!

1 Like

Thank you for your post, as my daughter is also newly diagnosed, I can relate to your process! I do not have the advise of someone with experience, but was wondering if finding a good endocrinologist would help, as you mentioned that your pcp is prescribing the insulin. Our endocrinologist and nursing team have been so helpful with specific carb ratios, guidelines for exercise, and overall strategies and I don’t think I could have figured it out on my own. Also, things seem to change week to week in the beginning, so being able to have the doctor review the glucose numbers and make changes has been so important. That’s wonderful that you have a cousin who is a diabetes counselor, I hope that you find all the support that you need!

Dennis, a follow up question re: insulin stacking… I have been trying to figure out this concept! Eva is 13 and a growing teen. She often likes second helpings or a snack or sandwich an hour or two after dinner. I have been giving her the insulin to cover the carbs, but never a correction based on glucose reading at those times. We only give corrections at mealtimes. Does this sound right to you? Any risk of stacking here? Thanks, always for your guidance with all of your posts!

Hi…I am recently diagnosed also I have found the best books to read are “bright spots and land mines” and “think like a pancreas” these are extremely helpful to a person just diagnosed…
I do use a cgm and am able to now have good control a good percentage of the time and I do exercise (walk for 30-40 min after dinner or lunch most every day)
I have learned so much from just reading and this forum… if you would like you can message me…


Hi Ariana @jimjamz, as I suggested, many others would read your post and offer you a broader picture with their suggestions; each of these posters has very good advice. In addition to answering your exercise questions, I will tell you that you shouldn’t get too complacent in diabetes management just because it appears that you have several days, weeks or months where you remain “in range”; your balance can be thrown off for many reasons that are beyond your control, such as hormones or change in season and temperature - you will then need to make adjustments. Be watchful but try not to let diabetes rule your life.

Exercise affects everyone differently and as Dassy @Deeeerose points out aerobic exercise generally lowers BG while anaerobic exercise can boost BG significantly. I find it “safer” to begin exercise after eating and depending on my intended activity I adjust my meal bolus slightly to lessen the probability that exercise will lower my BG; I use an insulin pump and reduce all insulin for aerobic exercise.
Extended exercise can cause my BG to drop sharply several hours later, even when I have a meal after my exercise. Often, if I exercise extensively in the afternoon and then have a usual supper, my BG will sometime drop sharply about 9:30 PM. The key is, check your BG frequently during and after exercise.

Hi Cathleen @cminer, I agree with your daughter taking insulin only for the carbs eaten during her “snack after meal” and not for any correction because of BG reading. Also in a situation like this, unless her BG is much higher than you would expect, that you give her a little less insulin than what is calculated for the snack - especially if the snack is in the evening before her bedtime. A “high” can always be corrected later or in the morning. If I am to err, I go by my rule that I’d rather be a little bit above range than to be hypoglycemic.

Thank you too Cathleen for your compliment. Just yesterday, during my regular visit with the endocrinologist, she asked me if I would accept a call from another of her patients who asked for guidance; over the years, she [the very good endo] has asked me to talk with several of her other patients.


I also agree with @Dennis, if you eat 7 times and only inject for the carbs eaten, it’s not “stacking”. Stacking ONLY refers to a bolus you took for a meal, followed up by another bolus to bring down that high.

@jimjamz Ariana, there’s 2 sides of every story. Synthetic rDNA “fast” insulin still stinks. so if you eat plain table sugar or glucose, it’ll absorb and raise your BS faster then the insulin will take care of it: result temporary high blood sugar that will come down at the 4 hour mark if you took the right amount of insulin AND accounted for the average level of exercise.

They say not to eat unless you are below 140 mg/dl, this is because the typical “diabetic” meal will peak and then return to 190 mg/dl at the 2 hour mark… at the 1 hour mark? well that’s anybody’s guess. at the 4 hour mark it’s back to your starting number of 140, unless you added a little and then (say added a unit… for me), I would end up at 108 mg/dl.

ideal blood sugar is always below 140 and fasting below 100. you can do it with keto or low carb diets and fanatic blood sugar testing but you risk a lot of lows. in the medical world, lows are more dangerous than highs… but it’s the highs that wear us out over time. in my little world, I don’t react to a post meal spike of 250 and I don’t freak out unless I see a number north of 300.

when travelling and at restaurants, where they hide carbs in the air and in the water, I do look at the 2 hour mark and either add insulin (purposely stack) or walk or treadmill or climb the fire exit stairs because either way, my goal is to return to normal at 4 hours and to not sleep on a 250 or 300. Walking, with insulin on board, can drop me 100 mg/dl in 30 minutes or less so I prefer the “add exercise” over “add insulin” every time that I can.

advanced topics in restaurants and peak reductions are in your futures. please don’t try to learn it all the first .year… and always always have a carb source on or very near to you.


@joe, thank you. That was exceptionally helpful, and I really appreciate it. I haven’t heard, until now, that’s it is recommended not to eat unless you’re below 140, I thought you would just increase insulin to account for the high number? And when you say:

Do you mean you don’t “react” as in feel any physical difference? Or you don’t react emotionally and get upset. Because when I see high numbers I inavariably get stressed out. Compounding the issue… I’ve had anxiety for most of my life. It’s a tricky thing when combined with high blood sugar readings. Exercise is the most helpful thing for both cases, but I just can’t manage to do it every day :confused: before I knew I was T1D I thought I had candida because I was so itchy! -_- then I thought it was a kidney infection, then the doctor called and told me to go to the ER because my BG was soooooo high. What a relief it wasn’t an infection. Just diabetes… ha. I’m trying to figure out my signs of high bg, but Im not noticing any.

@Deeeerose thank you :slight_smile: that was really helpful. I walked into taking insulin thinking it would be a requirement regardless of exercise being involved. I had a lot of preconceptions of what it means to be diabetic and sooooo much to learn :confused: it is in fact very helpful to know you can sometimes lower the amount or potentially pass it up if you’re exercising. Diabetes is like a lifelong practice in being flexible haha.

@ger thank you for the book suggestions, I’ve just gone and purchased Think Like A Pancreas :slight_smile:

@cminer & @Dennis thank you both! That was important for me to read and know about regarding the potential of snacking after a meal. Everything from everyone is really so helpful to me. I’ve gone from being completely in the dark on how to be T1D to being shown the light! Haha. I’m very grateful for everyone’s replies and support :slight_smile: this

1 Like

@jimjamz HI Ariana, both really :slight_smile: “react” as in get angry and inject more insulin.

And you’re right - I often eat a meal above 140 by a combination of bolus for carbs and bolus for correction at the same time. The idea of not eating a carby meal above 140 is to avoid a huge post meal spike. Say your are 230 mg/dl and eat a 45 g carb lunch… you could very easily be in the high 400’s at 1 hour even though you did the math right and you will hit your target at +4 hours. During the 90 minutes of extreme high blood sugar, you are changing water retention and probably blood pH and electrolytes because of the way your kidneys deal with super high blood sugar, even if it’s temporary. That’s really where the “140 mg/dl rule of thumb” comes from. I just eat no/low carb when I am high and hungry.

all I can say is for high blood sugar I get leg cramps a sticky feeling in my mouth and a general feeling of exhaustion (electrolytes and dehydration). Everyone has differences here, these feelings are not as typical or as profound as for a low.

@joe Ah! The 140 rule makes sense now. It would’ve taken me a while to riddle that out. So, thank you! It seems like an important thing to know early on if I don’t want to stress out my body any more than I have to. You explain things very well.

Hi Ariana! I’m curious if your PCP will be referring you to an endocrinologist? And are you only taking fast acting insulin before meals, no long acting such as Lantus or Levemir?
It’s interesting to hear other people’s stories. My daughter will be 4 in April and was diagnosed in October.
We have carb ratios that change often and are different from meal to meal. We don’t correct in between meals, but use her BG number before the next meal to measure the success of the first dose of insulin. Her target number is 120, so if she’s above that we take the difference and divide it by her correction factor to get an additional amount to correct. If she’s low before a meal without a reason (exercise or incorrectly counted carbs) we change her ratio. If she’s high 3 times in a row for a particular meal we change the ratio. And her number when she wakes up before breakfast measures the accuracy of her Lantus. She often spikes very high after meals but is within range by the 4 hour mark. You’ll also soon figure out what foods might affect you differently. Fiber is your friend. And I second or third the Think Like a Pancreas book. Good luck, and just be aware there are so many factors that affect blood sugar. You might have a great week and the next is a roller coaster but you’ve got this.

So much good advice ! Read it all, and apply to your own case — it will be different from anyone else’s, so be aware of that.
Be aware of what you eat ( how many carbs – and cover it with 1 unit for each 15 gm of carbohydrate, BEARING IN MIND that there are fast carbs and slow carbs— so you may go high right after you eat, let;s say, a donut — and then go plunging down. (After which you may try to compensate with apple juice — and overdo if you keep sipping) so have a bit, and keep checking your sugar every 15 min. On the other hand if you consume a slow carb — say, 15 gm / one slice of low glycemic bread — you will not plunge low, and therefore not need to raise your sugar with juice (fast fast carb).
Experiment and keep track so you know how you react. Don’t do anything drastic. In a detailed log indicate # of hours you expect your fast-insulin (e.g. NOVOLOG) to be viable ( usually peters out after about 4-5 hrs.) So dont inject more, should
it be sending you high. Live with it. its just a few hrs. High sugar won’t kill you — low may be worse – although its easier to fix --with apple juice or 5 sugar ( not diet!) life savers and such.
For a high — its OK to fix with tiny amounts of fast acting insulin — I did say TINY! And keep checking. (Make a 4-5 hr. graph and watch it!)
Low sugar CAN be easily fixed – but not good to get it, as it will give you cardiac arrythmias — something we definitely want to avoid!
When I look back on my detailed record books of the last 12 years ( how long I’ve been TiD) I find a lot of readings that I was too scared to fix. Now I know better! Learn to deal with it, you will be soooooo much happier BEING IN CONTROL! It’s your life, don’t let diabetes rule you! You rule it!
Good luck!

@Fiora and @mkurkov thank you both for your respective wisdoms on this. I’m seeing my primary care tomorrow and have an ongoing list of things to ask her, which includes a referral to an endocrinologist. I am on a long acting insulin, I don’t know how the amount I use, which is the same every night, affects me during the day. How would I know if I needed more? The biggest discrepancies in my numbers are a result of exercise, or lack thereof… my goodness, it changes everything. I’ve also noticed that my running has become sooooo much better and more efficient since I’ve started using insulin. It’s crazy… have others found this to be the case as well? I’m kind of shocked by how much more functional, clear headed and stable my emotions are. I suppose my body has been doing the best it can with the onset (however long it was developing before I even knew) of diabetes, but when it has what it needs to function correctly it does so well!

A p.s , Ariana… among the things I learned the hard way ( experience) is that exercise does not always lower your bs — if you start with a high it may actually raise it, depending what you start with. My best starting number for 30-40 min. of walking is in low 200’s. That will come down to @ 100. Not always, of course. Sometimes the very same scenario will lower me 20-30 points or less.
The other surprising thing was going down to @45 after a leisurely after-dinner stroll on the beach with family while vacationing. And it did not happen right away, but a lot later, around 10 pm if I recall. So, I learned eventually that the effect of exercise may last a lot longer than the initial drop.
The solution is to know yourself, know what to expect and test frequently . As I said before, the lows are easily repaired… as for the highs ( which will happen for a number of reasons, alas) there is such a thing as fast acting insulin I am told ( and I don;t mean the standard NOVOLOG type.) — but I understand that it is tricky, possibly only administered by professionals, like in an emergency room.Need to learn more, but I would err on the side of caution. Live and learn!
Stay strong!

I am not a professional, but have had type 1 diabetes for 29 years now, have hypoglycemic unawareness but as far as injecting after eating to correct a high bs, it depends on different things. When was the last time you injected insulin? If you take a shot/bolus-via insulin pump within four hours after the 1st shot/bolus, it is considered “stacking.” My endocrinologist advised that if my bs is over 200 mg, it is ok to bolus to bring the bs down. High blood sugars damage everything in the body.
Best advice is to check with your endocrinologist, not general physician for all your questions.

Hi, and welcome to the forum, and to the diabetes family. I’ve been on insulin since 1963 myself. I’ve only glanced at a couple of the responses so far so what I’m saying may be a duplicate but I’ll throw my hat in the ring, so to speak :blush:. I noticed you got your instructions from your PCP. Be sure to find a good endocrinologist who is board certified in diabetes. They have the best knowledge of what you need to do to manage your diabetes, fine tune your insulin needs, and determine insulin/carb ratios, how and when to correct, etc… They may set you up with a diabetes nurse educator (DNE) as well, who should be able to answer any questions you have between doctor visits; and a nutritionist who can make sure you are on the right track with healthful living practices. Definitely find specialists in the field - they’re the best ones to help you learn about your diabetes and give you the guidance to stay on track.

I have seen many doctors and many specialist after 50 years of Type I and that is what you need first and foremost, 1. Diabetic Patient Educator 2. Endo or diabetologist 3. Nutritionist

  1. Patient Educator will spend the necessary time with you so you can start tracking your condition. They are up on the latest tools and devices and have the collective experience of 100s of diabetics with all kinds of other medical issues in all kinds of occupations or school situations.

  2. Endo, These docs specialize in diabetes, so they will see things your PCP doesn’t. There is no real diabetic training in medical school other than how to remedy a low bg.

  3. Depending on your own knowledge this could be helpful, following a kedo diet is not necessary and my not provide the necessary nutrients for a healthy lifestyle. Counting carbs is a necessary skill for all diabetes, Type I and II.

I would not put much into any diabetic treatment advice from a PCP unless they are a diabetic. What you need is good data about how your body deals with carbs and the insulin that you are injecting. The best way is to use a CGM, but finger sticks will work, but plan on one b4 meals and one after meal and one for any other event that effects bg, e.g. exercise. Exercising when you are already above 200 mg/dl can raise your bg. If I am high after a meal, I wait until my bg is below 250 b4 starting my exercise or I start by just walking until my bg drops. The rules others have suggested may work for them, but you will be better served by following specific metrics from your own bg data points and past experience on doses of insulin per grams of carbs. I use 10 grams of carbs requires 1 unit of humalog or other fast acting insulins. I also do insulin corrections equal to 1 unit / per 50mg/dl of blood sugar drop required, assuming that my IOB (Insulin on board)is exhaused. These ratios are how all insulin pumps determine dosage required. You may not be ready for this level of prescribed therapy. Every insulin has an action curve so check out these graphs on your brand of insulin. The 140 mg/dl rule about eating is something I have never followed. 140 mg/dl is almost a perfect level, although most diabetic drs will set something lower, because as is human nature, we always fudge when we have to sacrific.

@wadawabbit has the best answer and I agree, Be sure to find a good endocrinologist who is board certified in diabetes. They have the best knowledge of what you need to do to manage your diabetes, fine tune your insulin needs, and determine insulin/carb ratios, how and when to correct, etc… They may set you up with a diabetes nurse educator (DNE) as well, who should be able to answer any questions you have between doctor visits; and a nutritionist who can make sure you are on the right track with healthful living practices.