The Metformin arm of the STAMPEDE trial did suggest men on life-long hormone therapy should be offered Metformin too. Sadly it didn't significantly help with the cancer, but it did help avoid or reduce long term metabolic side effects of hormone therapy.
There's also a UK expert in this field who has for some time before that been saying all men on hormone therapy should be offered Metformin and a statin as a matter of course, just to compensate for what hormone therapy does. This isn't currently NHS/NICE policy, but something you can ask your oncologist and GP if they're willing to do, and certainly, you should have your doctor regularly monitoring your blood glucose, cholesterol levels, and blood pressure while on hormone therapy, as it tends to push them all up, and medication adjustments may be necessary. For cholesterol, nowadays they tend to look at the HDL ratio, but as HDL is no longer a good cholesterol when you have no Testosterone (or more strictly, no estrogen), it's the total cholesterol level you need to monitor, not the HDL ratio.
This probably doesn't apply to those who are only on Bicalutamide.