I don’t drive HGV but I do have a class 2 truck licence for ambulance driving. I also work shifts. I have to blood test two hours before driving and every two hours (at least), as per DVLA rules, even though I use a Dexcom CGM (I’m just a student paramedic so not yet blue light trained, but I’m doing the blood tests as if I am driving). We have to have 11.5 hours rest between shifts, but we don’t use a tacho, as the crews alternate driving and attending a patient - also there’s an exemption for emergency services.
As for nightshift blood sugars, I wonder what insulin regime you’re on? I’m assuming injections if you’ve just started insulin? I’m pumping with a DIY artificial pancreas system, so it handles things for me pretty well, I have an override setting for work which runs me a little higher than if I were at home; I aim to keep in the 5-6s rather than the 4-5s I do on rest days. I usually take 80-90% of my normal doses on a nightshift. I eat a low carb meal (usually some roasted veggies and some tofu or egg for protein) when we get a meal break, as I don’t need to take extra insulin for it, so I don’t have loads sloshing about when we go back out. And of course I carry dextrose tablets in the pockets of my trousers and jacket just in case. I set the low alarm on my watch (it’s all integrated in my pretend pancreas cyborg system) slightly higher to 5mmol, so I can head off even a marginal low before it happens. It’s usually set at 4.3mmol.
If you can get Libre sensors they’d help a lot - with a little add on transmitter you can turn into a constant glucose monitoring system complete with high & low alarms on your phone and even a smartwatch. DVLA don’t accept them for driving so you’d still have to test every two hours, but it would alert you to an issue before it becomes a problem.
Good luck with your first day back x