Your nocturnal sugar spikes seem unusual. Typically we would expect your sugars to run 80-100 through the night. Some will even drop into the 70s. Perhaps the good thing is that, from what I saw, the spikes seem to be staying under 140.
Whereas, there is definitely a dawn phenomena, the cause of spikes in the middle of the night are a bit more mysterious. In medical school, we never really studied continuous glucose monitors in non-diabetics so there really is no clear and common differential diagnosis of which I am aware.
Previous research definitely shows a correlation between sleep apnea and blood sugars and it would make sense that nocturnal hyperglycemia would be the source. It definitely makes physiologic sense that (an) episode(s) of hypoxemia from sleep apnea could spike epinephrine in the blood stream and thus cause a rise in blood sugar.
If it is sleep apnea, yours could the first case of apnea diagnosed by continuous blood sugar monitoring. It could definitely be case reportable. We could search PubMed to see.
I recall seeing that there are iPhone apps that record sound through the night. (Some are used to record sleep talking - like the Sleep Talking Man blog.) It could be interesting to see if you catch anything - and if you do - whether it occurs before you see a spike in your sugars.
I am happy to prescribe any other diagnostics as well to get to the bottom of what might be the cause. I increasingly get the feeling that this continuous glucose monitoring is going to open up a whole new diagnostic world...and to think...given the latest news this week...it sounds like the next Apple Watch might even have a watch band that does it. It will be a new world.