Is it normal for BG to go up after Lantus injection?

Yesterday, V’s BG was 70 at 2pm, (after lunch); he had a small snack to correct the low and it was 117 at 4pm - which is good.
At 7:00, when it was time for the Lantus he was at 197. He took the usual bolus for our usual tea/snack, but his BG continued to rise to 240 by 10pm - when we had dinner.

He took the usual bolus for dinner and at 2:30am, when he checked again, it was at 112.

This morning it was 240 again.

Is it usual for the BG to rise just prior to the next injection for Lantus - on a once per day routine - and is this why people switch to twice?

Is the rise to 240 normal for the ‘dawn phenomenon’?

(We’re going to check more frequently tonight…

Actually, one more - could this erratic behavior be attributable to his doing nothing for 5 days (while in hospital for a check-up and the switch to Lantus) and then being very active?

Any opinions greatly appreciated. He’s been using the Lantus for 5 days… (switching from mixed)

The day before all his readings were near perfect - except for an afternoon low.

14:00 70 mgdl
16:00 117 mgdl
19:00 197 mgdl Lantus time
22:00 210 mgdl
02:30 112 mgdl
07:00 240 mgdl

It is much to early to jump to any conclusions here. Two insulins are operating and carbohydrates have been eaten. So several causes for the rise are possible including different activity levels (hospital vs home) as you have written:

  1. in your case Lantus may not last for 24 hours. In this case the rise will begin just before the next Lantus injection. The rise can also last for some time until the newly applied Lantus has started to be effective.

  2. the measurement for the carbohydrate intake may be incorrect

  3. the factor ‘carbohydrates per insulin unit’ (USA) or the factor ‘bread units’ (GERMANY) may be incorrect or different for different phases of the day

In this order the cause should be ruled out. Without the proper amount and injection scheme of the basal insulin you will be unable to achieve good control. So point 1. is most important and can be determinded by fasting for 1/2 day. If you start fasting after lunch (1:00 pm) you must reach normal blood glucose around 4 pm or earlier. If you measure at 5, 6 and 7 pm and you see a rise then something is wrong with the Lantus dose or it is not working for 24 hours. It is very important that you have reached normal values before the rise has happened to be able to draw this conclusion. This test is normally done in the hospital but I am not sure how the procedures in France will handle that.

Would you like to create an account for V on our free project so we can follow his progress for some time? You can contact me directly if you have any questions. Holger

Thanks for the suggestion. I did set up an account… What next?

Katie, you are a pro already! I would say that you answered all your own questions. The rise could be due to the previous Lantus wearing off before the new injection set in.

The morning high could likely be the dawn phenomenon, which is hard to fight unless he goes on a pump. Has his blood sugar been high every morning or just some mornings?

At 7pm when he took the usual bolus for a tea/snack, did he eat a snack right away? and did he give a correction for his high blood sugar? When he is high, he should be adding some insulin to the normal bolus (as long as it has been 3+ hours since his last injection of fast acting insulin).

While you are trying to figure out all the rates, it is especially important not to give fast acting insulin more than every 3-4 hours. Otherwise, it’s hard to know how much is working from the previous system.

There is a good bolus calculation worksheet that you can use to fine tune his rates (but you need to enter a starting carbohydrate and correction rate). Click here

Hello Katie, the Diary of V can now be visited with the following link:

I have seen that you have already entered two days of his diary. The community will follow V’s progress and the more data we have the more likely we will see repeating problems that can be adressed. I think it will need at least one to two weeks of data to give you the first feedback.


You can stop to share the diary with the community at any point in time. Just logon to and delete the share called “TuDiabetes - Lantus discussion”.

When he was in hospital the docs never wanted him to do corrections, so we’re a little nervous about that. So, the answer is no, he didn’t do a correction. He’s going to start.

He’s taking 9 units of Lantus and 50 of Rapid each day. I think those numbers are not right. I think he should be taking more of the Lantus and less Rapid. He’s getting lows after breakfast and lunch.

I guess we’ll just be doing baby steps until we get it fixed. Our diet and his activity level are just so different than when they started him in hospital.

So, he should always wait 3 hours before giving more rapid? Is their a way to determine how much Rapid to take, without food, just to correct a high? Or is it trial and error?

Quote: I think he should be taking more of the Lantus and less Rapid. He’s getting lows after breakfast and lunch.

To me the relation of 9 Lantus to 50 Rapid seems odd too. In the diagram ‘Glucose - Curve’ the insulin seems to act like an additional basal insulin because of the high dosage (the higher the dosage the longer the insulin will be working). In my opinion you should seek for a specialised doctor called diabetologist. He knows fasting tests to determine the correct relation between basal and bolus insulin. I guess you will come out with something like 16 Lantus to 40 Rapid. But this is just a guess.

Quote: Is their a way to determine how much Rapid to take, without food, just to correct a high?

Yes, there is a rule of thumb: you can assume that one unit of insulin brings you down 30 mg/dl. For most people this will fit. Some will be more sensitive so they apply the 40 mg/dl rule. Now just take the high number and subtract your target value (240 - 110 mg/dl = 130 mg/dl). Then divide the result by 30 (130 / 30 = 4 units). This type of calculation is done automatically by the ‘New Entry’ wizard of Glucosurfer. In the settings you can enter the correction rule for every hour.

The curve for Monday looks a little smoother. How do you calculate the dosage of the rapid insulin? Do you have some rule that you apply for the amount of carbohydrates?

I’ve been trying to work that out. Nothing the docs at the hospital did seems to make sense according to everything I read… To ask them for help would just involve another hospital stay, and hospital stays and real life don’t seem to have much in common when it comes to insulin. Today, we’re working on 1 unit to 10 grams, I think the Rapid was causing the lows. We increased the Lantus by 1 unit again, also…

Thumbs up for the Lantus increase. It was not the Lantus that caused the low in the night. I think the rapid dosage at 22:30 for the 45g of carbs was to high and this caused the low in the night. For the next week I would recommend to eat the last carbs before 20:00. This way the rapid insulin will not be active in the night and you will know at 23:00 if you need a correction or not. It would be ideal to have a good value before going to sleep. This way we will know if the Lantus dosage is high enough to reach good values in the morning phase.


Looks much smoother but this seems to be related to the high dosage of rapid insulin.

The phase after 15:00 shows an increase and the question is: caused by overeating OR is Lantus missing?

The high at 22:30 may be related to the Lantus gap between the two Lantus injections. This can be compensated by reducing the carbs per insulin ratio from 18:00 to 22:00. Thus more rapid insulin will be injected. A gap can not always be compensated this way but it is worth a try.


To eat earlier at 19:30 shows that the rapid insulin in the late hours has been also effective in the night. Now by eating earlier this rapid insulin is missing. Even corrections in the night could not prevent to reach 311 mgdl in the morning.

As a conclusion I would still think that the Lantus dosage should be increased. This also means that a time will come were the rapid dosage must be reduced because the rapid insulin is now doing part of the work that the Lantus is supposed to do. So keep on with the high test freqeuency (one additional test at 17:00 or 18:00 would be fine) and be prepared for some lows to happen.

Thanks for the input and help. It is really appreciated. I think he started the night high partly do to stress (the power went out during a storm and the television blew a circuit - and he couldn’t get anything to work for about 30 minutes)
Also, we we’re trying to not have an overnight low, so we reduced the bolus. We wanted to see how the Lantus would work with no food for 10 hours. Since the BG went up we know we need more. The two previous nights he had a snack to compensate for the lows.
It’s a great relief to have someone else watching over my shoulder. As I may have mentioned, the doctors here would just put him back in hospital, fix it to their satisfaction, then send him home so we could figure it out all over again.

Lantus doesn’t last for 24 hours for everyone (less for most, I believe).
I switched to taking half in the morning and half at night a while ago and that seems to behave much better for me.
Maybe try it for a few days and see how it goes (though, for lantus, you probably need to give it a couple of days after making ay changes to observe the results before changing further).

Hello Katie, how was your progress so far?

I haven’t read all the posts so this may have been said already. My endo has suggested to me that you should be taking roughly the same amount of lang acting as you are of the fast acting. So for me I take 20 lantus in the morning and 18 at night and around 40 units of humalog everyday, when I eat regularly. Both insulins have to be adjusted depending on how much exercise I’m getting, but it’s a basic formula that has worked for me.

It sounds like that would be a big change so talk to an endo before trying this, of course.

Thanks for the info. Everything has been really crazy but we’re slowly tightening it up. When he came home he was taking 8 Lantus and 34 Novolog for breakfast alone. Now he’s on 13 Lantus and 12 for breakfast (the other meals have been adjusted as well…) It’s slowly improving… We appreciate the help.

We lost internet last Thursday so we’ve been on our own, so to speak… I’l be catching up soon.

Holger and Katie: we are all different for Correction Factors. My own Correction Factor is one unit lowers me by 112 points (because I am on a small TDD and insulin sensitive. So I haven’t even done a correction yet because I would have to be 212 for it to be safe and I no longer get that high. “Using Insulin” by John Walsh has a good explanation of how to determine Correction Factors.

I have the numbers posted from the last few days I think we are slowly getting a handle on it. But I am puzzled by the dip he takes after breakfast… which is his highest carb meal of the day.

Info for all readers of this thread: please klick on the following link to visit the diary that is discussed here

Hello Katie,

thanks for updating the diary. While looking at the new data I had these ideas:

  • it is hard to figure out what is wrong: is it the lantus or is it just the carbohydrate factor after lunch and in the evenings that does not fit?

  • saturday (july, 25) in contrast looks very promising. It is smooth with no wild swings but the mean level needs some improvement. The same day with 2 units of lantus more would look nearly perfect. At the same time the morning levels would have been a little to low before lunch so the carbohydrate per insulin factor for the morning must be changed to reach normal levels.

  • could you set the carbohydrate per insulin factors in the settings? This way we will know how the dosage for the rapid insulin is calculated.