Type 1 Curious About Rising Bloods

51 years on insulin in Oz.
Hi Samowen,
It may be that you have discovered what is called the Dawn phenomenon or effect. You will need to check with your DN and doctor to confirm this.
According to my reading and my own experience, the Dawn effect usually starts around 4 am and so would seem to fit the time sequence you describe.
At 4 am, the 'body clock' starts to prepare each of us for waking up. The adrenal glands shot out cortisol hormone (steroids) at that time. Cortisol tends to increase blood sugars in readiness for us to face the day. Because we cannot expect our own pancreas gland to be able to handle that sugar 'boost', and if your insulin is pretty flat in its effect on blood sugars around that time, the sugar spike or Dawn effect is exposed.
I am lucky enough to use an insulin pump and my doctor can program the pump to release an extra boost in short-acting insulin, say, from about 3 am to 6 am, to cover the sugar boost (Dawn effect). It is not so easy with insulin injections.
I would suggest you discuss your results with DN and doctor and ask them how best you can deal with this. You have a right to expect some answers and not be told that it does not matter.

There are many reasons for our BG to rise: more/less exercise, food (something fatty may take longer to affect your BG), more/less alcohol, stress, drugs, sickness, time of day/year, weather, too much/little sleep ... our bodies are very fickle.

Is the scenario you describe normal (going to bed around 9.0 and waking at 12.4) a one off or normal? If normal, the explanation of Dawn Phenomenon from @kitedoc is quite likely (although the time varies for each of us). Otherwise, it could be something else.

Regards to your very understandable concerns about night time hypos, is there anything you can do to overcome this? For example, take some night time readings (either set some alarms through the night or trial a Libre). Might be a good idea to discuss this with your diabetes team as relying on a 9.0 reading is not ideal.

Edited to add a word of caution about using a Libre to provide night time confidence: some people have reported incorrect low readings when they lie on their sensor.

As helensaramay points out concern about nighttime hypos is real. I was much happier when my evening long-acting insulin was changed from Isophane (like Insultard) to Levemir.
The former could not be trusted to provide the same effect each time, due to irregular absorption, compared to the much more reliable Levemir.
And the other thing was the blood-sugar lowering effect of exercise in late afternoon/evening, causing hypos in the early hours if precautions were not taken. I would lower the evening short-acting and long-acting insulins by at least 20% on these occasions and make sure I had some carbs with dinner and supper. And that still did not get me out of checking my blood suagr about every 2 hours through the night, just ion case I had miscalculated !!