Insulin dosing interval

Hi all

I'm new here. My daughter Madeline is 6 and she was dx with T1 in early March after going into severe DKA and nearly died. We're still learning about BG management. Some days I feel like I "get it" and other days things seem so erratic that I don't think I've figured out anything at all.

My question is about insulin dosing, in terms of how often. Right now Madeline gets insulin with every meal but not snacks, and also Levemir at bedtime. During the school day it's easier to keep her on an eating schedule where her meals and snacks pretty much happen at the same times every day. Weekends is more difficult but we try. If we have her eat on a regular schedule then she's getting daytime insulin about every 4-5 hours or so. She's so responsive to carbs that her snacks during the day can't be more than 15g (if she's active) and 8g (if she's not active, such as a rainy day). But, there are times when she's just plain "starving" between meals and wants to eat way more than the snack carb limit allowed. Our endo team made it clear that we should not really withhold food if she's genuinely hungry. Like any kid her appetite ebbs and flows.

So my question is... say she had lunch at noon and got her insulin then, but then it's 2:00 and she needs to eat more than 15 carbs. If she does that, I have to give insulin again to her. Is this dangerous-- because it's been only 2 hours since her last dose and that dose is still working its wonders?  The same kind of thing happens near bedtime sometimes... she eats dinner around 6 but then wants a heftier snack around 7:30 yet it's only been 1.5 hours since her last dose AND she's going into bedtime.

I would love to know how people handle this. I'm at the point now where her endo is giving us a little more freedom to play around with the carb ratio to see what happens. I just worry about giving her too much insulin in a shortened time frame, yet she needs to eat more on some days-- either more frequently than the "Schedule" or more carbs when she does eat a regularly scheduled snack.

Thanks so much.


Hey, Heather,

This is a great question, and it sounds like you're "getting it" more than you think.  Just keep questioning and observing, as you clearly have been, and it will get easier the more you do it.

It sounds like you're using a long-acting (24 hr) insulin once a day, and then using a carb/insulin ratio with meals over 10-15 g of carb, which is what we are doing for our 9-year old son.  Are you also using a sliding scale correction for highs and lows?

This is what WE do as directed by our Ped Endo.  We cover every meal/snack over 10 g of carb with insulin according to that time period's carb/insulin ratio, and give a sliding scale correction for any BG out of range.  We try to wait at least 2 hours between eating so we can get a "good" BG reading, but if that is not possible, I still cover the meal/snack with insulin and may finnesse the dose based on his last BG test (a little less if he had been low or has been active, etc.).  My personal approach is that insulin to cover carbs if for carbs, and insulin for corrections is for corrections.  Insulin for corrections (called "insulin on board" or IOB) is "supposed" to stay in the system for about three hours, so if I gave a correction 2 hours ago and he's still a bit high, I don't correct again.  But, I DO cover carbs. 

Also, my son's system processes insulin differently based on the type of meal he has eaten.  If the meal is heavy on fat and protein, it's going to take longer to get the meal through his system than if he's had just a bowl of fruit, so I take that into account when I dose him; a bit less insulin for a fruit bowl, and a bit more insulin for pizza.  And, I never hesitate to test his BG if he seems to be going low; if he's dropping I can always correct with glucose.

I always recommend the book "Think Like A Pancreas" to people, because it really is a great, straight forward and easy-to-grasp, detailed description of insulin therapies and all of the factors that affect BG.

Hang in there.  You're doing great.




Hi, my daugther is two and also is on Levamir and Novolog.  Its important that she eat her meals at the same time each day.  If she eats a later breakfast then she will eat luncher later as well.  She gets an afternoon snack at about 3-3:30 and evening about 7:30.  Her snacks are less than 15 carbs and if she is still hungry I give her a free food like string cheese.  In the event she eats more that 15 carbs she gets isulin to compensate for the carbs over 15.  I was told that she should not graze throughout the day.  She has to get her snack because more than likely she will drop.

The problem I have is that my daughter is a very picky eater, will not eat vegetables and wants to eat the traditional kids food.  I will cook a healthy dinner and she will not eat it.  I end up giving her what she likes so she does not drop.  I try to get the healthiest version of the foods she likes, i.e. hebrew hot dogs, whole grain pasta.  Any suggestions from anyone?  Also, I battle night time lows with her.


I will get that book. I've seen it recommended a few places. I like your description of the difference between using insulin to correct BG level vs. insulin to cover carbs. I understand this distinction in theory and of course both of these components are factored into her dosing but for whatever reason I still have trouble separating these ideas when talking about atypical situations. I too have noticed a difference in her body processing different kinds of foods. I have not noticed yet the way the insulin is processed but I definitely notice the kinds of foods that shoot up her level and the kinds that don't. I've learned not to give the fast acting carbs at bedtime (such as a sugar free popsicle) for example.

When you test before a meal, say, and then give insulin to cover that meal... and then your child eats about 2 hours later for a snack, when you test the BG is that number considered "real"? I don't know if I am explaining my question right. I mean, that second BG level is going to be elevated for Maddie because she ate a meal 2 hours ago and the insulin is still in her system from that. Do I use that before-snack BG on which to base a new dose? (this would only be if the snack were more than 15 g).... and as I type this I think I realize that it does not matter what the BG is, because I'm only going to cover carbs in a snacktime insulin dose, not correct the BG that's probably higher from the previous meal. Is this what you mean about insulin on board?

I'm not sure about a sliding scale for highs and lows... I don't think we do. Right now her carb ratio is 1:12 (sometimes 1:13 or 1:14 for inactive times of the day or close to bedtime) and for BG corrections we are correcting to 150/30. That ratio does not change no matter what her BG level is. I've wondered about that.

Thanks for taking the time to respond.


This is helpful, thanks. I struggle with the meal quality too. Maddie is a little picky. There are some fruits and veggies she will eat but these are ones that she can't have when her snacks are limited to 8 grams. It's very frustrating, honestly I think she eats less healthy now than she did before she was diagnosed. I say that because the amount of cheese and meats she is eating is much higher than it ever was. I hate having to reserve veggies and fruit for only mealtimes, that is so counterintuitive to me. Even when the snack limit is 15g, she can still not have very much so then she eats fillers like cheese and pepperoni to feel full.

I chase lows at night too. Last night was ridiculous for this. I realized that she either runs high or low at night, no in between. I would rather have her high to be honest even though I know that's not good over the long run. Her carb ratio is typically 1:12 but when I use that at dinner time she runs too low by the time it's bedtime. So I am going to increase that ratio a little bit over the next week to see what happens. I am not comfortable with her going to sleep lower than 150 because I find that she drops so fast. Like last night I put her to bed 3 hours AFTER her dinner insulin, her level was 165. She had even had a low carb snack before bed so I did not think she would drop much. But, I had a worry so I checked her an hour after bedtime and she had dropped to 100. I decided to give her juice and got her level up to 180 before leaving her alone for the night.

Hi Heather.

You are clearly doing really well if you are able to ask questions like this.  My son was diagnosed at the beginning of December, and I don't know as much about dosages!  Part of the reason for that is that he is on Novolog and Humolin NPH in the morning and Novolog and Levemir at bedtime.  The NPH carries him through daytime snacks and lunch (and it works really well--his A1C is great for a little guy), so I have to do less calculating, but I have less flexibility with food quantity or timing.  Every hospital and clinic seems to have a different practice, but you might ask if there is a different schedule that might accommodate your daughter's snacking a bit better.  We're also getting our son a pump (the company just called as I was typing this message!).  I don't know if it would make things easier for you, but it is worth a consideration.

Also, do you have somebody to call on a daily (if need be) basis about dosing?  If you do, use the service as much as you need to!  This is obviously an ongoing problem with your daughter, and somebody should be able to help you find a plan that will work for her (or at least work better).

I certainly have no answers, and I'm definitely no authority, but I hope this helps.



I think you are doing great. Yes, we were trained we needed to wait 3 hours after a fast-acting insulin shot before giving more. Otherwise, you run the risk of insulin 'stacking'. (Like you refer to the first dose still 'working its wonders'.) You can ask your clinic about how to test for how long the short acting is really working - in some people it seems to be mostly 'out' of their system in 2-2.5 hours, in other kids it can last longer - like 4-5 hrs. The average is around 3 hours. Basically, you'll feed her a regular carb meal, give insulin for it and then starting at the 2.5 hr mark, test every half hour until her level is basically the same 2 tests in a row. Probably would want to do this a couple times and take the average. (If you ever decide to start on a pump, this is helpful information to have).

In reality - I give my son what he wants to eat and give him insulin for it. As long as he is not low when he tests before a snack, I give the amount of insulin per the carbs of the snack. If he is low, (or on the lower end of range,) then I back off the insulin. If he's high, it becomes a little trickier. I would only give insulin for the carbs, assuming the early dose is still working, I would not correct. Ideally, if high, then give a free food snack at those times and wait until the 3 hour window is over to retest before giving carbs.

As far as free foods - I would give her as many carrots and celery sticks as she wants. Most veggies have very few carbs and so much fiber in the raw form that they shouldn't cause a BG spike for a 6 yr old. I agree I would much rather have fruit/veggies for snacks than cheese and sausage.

Thanks so much for your input. This is REALLY helpful to me. Thanks!!

You've gotten good advice.  The challenge you're having is balancing long acting (Lantus) and short acting insulin.  No ones body uses a steady level of base insulin all the time.  I took shots for 25 years and could never really avoid unexpected lows or highs, even with intensive insulin therapy when I was taking 6 shots a day (and this was back before Lantus, when you could take the long and short acting shots together).  When I started using an insulin pump it became so clear that it was the insulin duration times that were the problem, not me.  When I'm fasting my body has 6 different base rate that vary between 0.4 and 1.5 units an hour, depending on time of day.  No wonder I was having lows at some times and highs at others!  

With shots it is best to dose insulin based on blood sugar and food actually eaten, instead of trying to make your child eat when he or she is not hungry or restricting food .  In my experience, ALL kids are crazy hungry when they are in a growth spurt.  You can't ignore their need for extra food.  Forcing or restricing food can also lead to eating disorders in the future (super common among diabetics).  

So keep doing what you are doing.  If your child is extra hungry, you can give an extra shot or just let blood sugar be higher for a couple hours until you give the next shot.  

Dosing insulin really is an art, not just a science.  I've had type 1 for more than 30 years and am always learning something new.  Don't be discouraged by that, just know that dealing with this will help make you and your child into quick and creative problem solvers.  You'll also get REALLY good at math and be able to divide any number by whatever your child's  carb ratio is!