You would need to test his blood sugar to know. Pre diabetes and diabetes can have many symptoms, shakes can be one of them, but it could also be from other things too.
You should go to the pharmacy and buy a blood glucose meter, check the side of the box, but most come with 10 test strips, and they run about $20-30. So it's everything you need to check.
Or you can go to your doc and have them do a glucose tolerance test.
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