Not intended in any way shape of form as medical advise, I am not a doctor.
The above said, I shake like a dog passing a peach pit, most especially in my hands. Propranolol helps me with this, even when not keeping my blood sugar under control. I have what are called essential tremors due to nerve damage caused by my diabetes. I take a small dose, 10mg, 2x a day with meals. Oral doses have a pretty long lasting, 8-10 hours, effect for me.
Of course, your buddy should consult with his physician and his pharmacist about possible side effects and interactions with other drugs he may be taking.