| Yes, hate saying this but unfortunately 51 is certainly low enough to cause those symptoms, in fact anything below 72 is a cause for concern. The really horrible thing (and I hate having to be the one to break it to you) is that, since you are newly diagnosed, your blood sugars have been at an elevated level for some time which means you are actually going to be much more sensitive to lower blood sugar levels for a while. When I got diagnosed, if my bg ever went below 90 I was getting hypos.
The good news is that this won't last, after a few weeks your body will normalise itself, but for the meantime you are going to have to be careful. You're on a pretty good insulin system, the one I used to be on before they moved meto Lantus, so you've got quite a lot of flexibility.
As for stress, it will raise bg levels, but here's the thing. You say you've got a heavy workload, which means your brain is going to be steaming overtime, and that means it's going to need sugar. Mental exercise burns up sugar too, maybe not to the same extent as physical movement but it's still significant.
The best advice I can give you is to always carry glucose tablets with you at all times, and maybe get a Medi-Tag or something similar so in an emergency people will know that you have diabetes. Most importantly DO NOT BLAME YOURSELF. This is not your fault. The learning curve for diabetes is unfairly steep, but as long as you don't let your condition overwhelm your personality then you'll get there. Don't be embarressed. F*** what other people think, it's their **** problem, not yours, and if you spend your life worrying about what other people might think you'll never get anything done. This might sound really militant and aggressive, but trust me, it works.
On a more practical side, deconstruct your hypo. Look at how much insulin you took, how much you ate beforehand, any physical/mental activity you did. See if you can identify a cause, because then you'll feel more secure in your knowledge. Another tip I'd suggest is to try and remember how you felt just before the hypo. Maybe I'm lucky or something, but I usually get this feeling about five minutes before I go low. I can't really describe it, but I just suddenly realise I feel a bit 'off' and I'll chug down a few glucose tabs just to make sure. If in doubt, eat some sugar because in my opinion it's better to be slightly 'high' than have a hypo.
Good luck to you. Given the choice, none of us would have chosen to have diabetes, and I'm afraid there's no other option available yet other than having to put up with it. Much as you might not believe it though, you WILL get on top of this, and what's more, you'll be a better person for it too.  | 
