I recently decided to start splitting my Lantus dose. I tried this a few years ago, before I started doing so many studies, and didn't find it helpful. Recently, however, I became convinced that I really needed to. If I took Lantus in the evening, with dinner or shortly before bed, my sugars were consistently very high around dinner and bedtime, and I was at risk of crashing in the wee hours of the morning. If I took Lantus with breakfast, my sugars were always very high when I woke up — and I'm talking in the upper 200s. High.
The reason for this is that Lantus isn't perfectly even across the entire 24-hour period. It has a peak around 2-3 hours after you take it, and tapers off over the last few hours of the 24.
So I started splitting my dose. I take half with breakfast, and half with dinner. It works out great because it's not as important that I take it at the same exact time every night, and I'm not having as many problems with highs OR lows. If you have problems with dramatic swings in blood sugar that you think may be caused by Lantus's peaks and valleys, I highly recommend talking to your doctor about splitting your dose.