I had the same thing happened to me for about a couple of months. I have several theories. Here is what I think was happening to me. After I stopped taking januvia I realized that it tore my stomach up and I had a very sensitive stomach. Any time I had stomach issues my blood pressure would should up to 190/100 and pulse of 100 bpm. I thought it was high blood pressure since before I was on 10 mg per day and it would control my bp. But after Januvia my bp was uncontrolable. So finally i got the BP under somewhat control by excercising, stopping Januvia and doing metformin only, and eating better. In about 4 months after stopping januvia I noticed that I would wake up with a server headache, shakes and the high pulse. I would go bike from 7 pm to 9 pm and have a night time snack. At this point my glucose numbers were comming down to a normal range, but I would get the feeling of a low when I was in the 70’s during the day. I started to think that maybe I was going low at night because I read an article that talked about type 2 body reacting to perceive lows during a period of time when your body is readjusting to normal numbers and night time normal low numbers would cause an adrenaline kick that would release glucose to the body to deal with the percieved low. They call it a false reaction. When the adrenaline kicks in your body gets the rapid heartbeat, the sweats, and then you woke up with a high and wonder what the hell happened since you have a high reading. This happened to me for about a month, then I started to get up every two hours at night to test the theory. Sure enough I noticed that I would go from 140 after eating a snack at 9:30 pm, to 120 at 11:30 pm. i would go to sleep at that time and wake up at 1:30 am in the 90’s and would be down to between 70 and 90 at about 3 am. Which was the time that I was waking up with the fast heartbeat and sweats.
So the next few nights I would eat a small snack at 1:30 am and then no more night sweats and fast heartbeats.
During the day we can feel the lows comming, but at night as a type 2 they come without warning and the body tries to manage with other means to get the percieved lows back to normal
Here is an article that kinda talks about this night time issue, but if you google on adrenaline and night time lows you should be able to find a lot of information on this type of issue
hope this helps or points you in the right direction