Can you get a libre (even just one) to see what’s happening with overnight levels? There was a free trial a while ago, not sure if it’s still on or not. It’s about £50 for 2 weeks data otherwise. No prescription required and available via a pharmacy (don’t forget you are entitled to vat free as a diabetic but you might need to check with them they have deducted that). There’s also a thing called adaptation glucose sparing aka physiological insulin resistance, that shows up as a morning stubbornness in fasting readings and misleading oral glucose tolerance tests. It’s purely a response to low carb and not pathological or harmful. It goes away within a few days of eating carbs should you ever need that test.