48 units of NovoMix 30 is equivalent to over 14 units of rapid acting insulin for the meal and over 33 units of basal for 12 hours - which sounds quite a lot to me for a T2 on a mixed insulin regime. If you're going hypo after one of the doses, it simply sounds like you've having too much insulin for your eating routine at that dose. If you eat at 6:30pm - but maybe don't have your breakfast until 08:30am, that breakfast basal (lasting 12 hours) dose is still potentially active when you add the second evening dose - only 10 hours later.
That was the problem I had, but the other way round, I was going hypo late morning, although my doses were pretty evenly 12 hours apart - it was just lasting longer in my system than expected - I calculated about 16 hours for me, based on BG readings. So if you eat your dinner at 6:30pm and have a hypo late evening, you're potentially experiencing the same overlap that I did - your morning basal is still active when you take your evening mixed dose.
But it's irrelevant what I think, this is a conversation you need to have with your medics - presumably there is a reason why they don't want you to mess with your eating routine - but having to eat enough carbs to meet the insulin needs seems backwards way round to me - your insulin dose should be tailored to your actual need based on food taken and BG readings. But I believe this was explained to you in another thread. I urge you to have this conversation with your team.
