I have been using Lantus for Type I diabetes for several years and only recently started having very high BG's (250-300) despite reducing my carb intake (went on an all protein diet for awhile, lost some weight). I noticed some overall insulin insensitivity (even to my novolog) during this period as well. I never experienced any detectable hypos during sleep (I inject the Lantus at around 9 pm)
I suspect that because Lantus is so flat in action, the low readings are undetectable but that the liver still responds as if hypo and releases sugar if the dose is too high, resulting in high BG's that even go higher as the dose of Lantus is increased. I tried increasing the dose of Lantus and found the morning BG went even higher!
This is what happens when Lantus is used for cat diabetics--I have a cat who had BG's between 300-400 for TWO YEARS and never showed any hypoglycemia. The high BG's were from too much Lantus! He is now stabilized
on 1/2 the dose of Lantus he was getting when his readings were 300+.
The only conclusion I can come to is that too much Lantus does not necessarily result in noticeable hypoglycemia but is indicated by a pattern of superhigh blood glucose results, especially in the AM.
Anyone else notice this? I've not seen any comment about this anywhere except in cat diabetic literature!

Although Lantus is not supposed to have a "peak" action, it definitely can be stronger (or maybe the body just utilizes it better) at certain times. If you take your lantus at dinner or bedtime, try switching it to the morning and see if that helps. Some people find they have to split the lantus dose into two half doses...am and pm, because it kind of tapers off at 22 hours and then they start running high...so if you're taking it in the morning, that could be happening.

The other thing to do is set your alarm for 3 AM one night and test...if you're going low, it'll show up and you'll know that you're having rebound highs, in which case you need to reduce your dose slightly.

Ruth

I'll honestly say I didn't read your whole post because I need to get to bed, but it sounds like a pump would help you a lot if that is an option.

... I suspect that because Lantus is so flat in action, the low readings are undetectable but that the liver still responds as if hypo and releases sugar if the dose is too high, resulting in high BG's ....
The only way you will know if this is happening is if you set your alarm clock every hour during the night and test. Better still, get hooked upo to a CGMS for 3 days. The graphs will show exactly what is happening to your BG levels.

I had a similar problem after switching from NPH to Lantus. I was sleeping through the night and, like you, I thought that high morning BG levels were the result of rebounds from mild hypos. But the CGMS showed that my BG wasn't dropping below 75. And I know that I don't get rebound highs from this level.

I realised that, with pre-bed NPH, there is a lot of insulin action from 4am - 10am. And that the flat Lantus action profile could be causing the morning highs. Splitting the dose just made the flat action more even and the high morning BG continued. So I tried replacing the evening Lantus with NPH and continued with the morning Lantus. And this has sorted the problem out.

My high morning BG was being caused by the DP effect, which I didn't notice when I was using NPH. I now inject 9 units of Lantus before breakfast and 5 units of NPH at night. And my waking BG is always in the target range. :p

Mark