Hi
@Taku and welcome to the forums. We're an international forum so there's usually someone around to chat, even though you'll find the forums are most lively in UK friendly hours.
Firstly, congratulations on the hba1c reduction. I would argue that that is the most important goal and that's an
awesome result. (And though 8s aren't necessarily a brilliant hba1c to have, there are many people who've run much much higher, so I wouldn't be too hard on yourself for having some years of erratic blood sugars in your teens and early twenties.)
As regards the blood pressure, have you tried exercise and/or weight loss (only if you are overweight) to reduce your levels? I did find my lantus went down a little when I went lowish carb, but my main reasons for it that I have a T2 father and a fair amount of insulin resistance, and lowish carb helps to keep my weight under control as well as my blood sugars. Though going low carb did reduce my bp levels slightly, I think the reason for their reduction was more because I made a serious effort to get fitter. (I'm naturally physically very lazy and the taking more exercise has made a massive difference to my well being. ).
Are you having to fund your own insulin? If so, then I totally understand why you might want to reduce the amount, but medically I think there is just generally a massive difference in how much different healthy T1s need, and you should just be happy that you're managing to match your insulin to your needs.
Once again, welcome to the forums and congratulations on an awesome hba1c result.