If your legs are getting weak with the risk of falling, then you need to see someone about it, and be able to tell them duration of symptoms, glucose levels, duration diabetes and medication history. It is not part of having diabetes and there are several possible causes. I have great respect for the nurses, but weak legs is a medical ie doctor problem, not a nurse problem
Not sure how long you have had the diabetes and your age.
I would suspect that it is the high glucose levels.
As above, I would wonder if glucose level too low which can occur first thing in morning, but you have stated levels too high and this might well be the cause. Also metformin and alogliptin do not make glucose levels go to low.
Blood pressure is often lowest in morning which could give same effect and could happen if on blood pressure tablets particularly if they got more effective eg with weight loss.
But you need to keep an open mind eg metformin is a great drug, but sometimes causes B12 deficiency which can cause weak legs / arms; there are lots of other causes of weak limbs.
Need to see GP and get things sorted
best wishes