My morning BG depends heavily on what I ate the day before, and the consistency of what I ate before. I find 4-5 balanced meals, with protein, roasted/boiled root vegetables, and some fruit with every meal, and my BG stays stable throughout the day, and the fasting BG moves way down out of "diabetes" level, or pre-diabetes, below 5.5. If I eat inconsistently, or eat more things like bread. rice, bigger protein meals, more fat, the day before, then I'm up in the "diabetic" range. I say it in inverted commas because I am able to get my fasting BG regularly in "normal" range through proper eating and sleeping schedule. I will be making a separate post about this. Magnesium the night before also makes a big difference to my morning fasting BG - ie magnesium lowers it. Exercising in the evening, or drinking alcohol, makes my morning BG rise. So it would be useful to know what you eat, and what your daily and especially evening routines are.
The issue at night, is that the body burns fat more than glucose (free-fatty acid metabolism). So you move away from glucose metabolism towards fat metabolism - this is called the randle cycle, or "glucose-fatty acid cycle", you can google it for more info.
So your body is not able to make use of glucose, hence why it rises in the blood through gluconeogenesis while you sleep (the liver senses the lack of glucose in the cells and creates it, in a broken feedback loop). The longer the nights, ie the more darkness, you may find that this gets worse (ie over winter).
Do you notice you have foamy urine when you pee in the morning? This is caused by raised fatty acid levels in the urine - the fat effectively is saponified by the force of the urine hitting the water, hence it foams up (in the same way that soap is created).
So you can (a) teach the body to metabolise glucose and store glycogen better throughout the day by having fewer wild fluctuations in BG - this is through smaller, more consistent meals, and for me at least, by having no grains and lower fat in meals and (b) use various supplements to help move shift the randle cycle towards oxidation of glucose over fat.
Insulin is not the only substance that controls BG - the insulin industry wants us to believe it is. Things like magnesium, potassium, etc also have huge influence on BG. And they're easy to test. Take some potassium or magnesium in the day, and check morning BG levels. Or eat foods with more potassium and magnesium.
High aldosterone creates insulin resistance too. Have you ever had a blood test of aldosterone?