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Generally doctors ask for basic blood tests, relevant to your condition (- to save your money).
If something abnormal is found, more tests are asked depending on the results.
You have not said anything except Diabetes
- so it is not possible to predict correctly.
There may be Hypothyroidism
- he might have done only T-4 first. T-3 and TSH
need to be done; some times more tests.. .
is common in diabetes - especially if not controlled well. That may be the reason to ask for ultrasound
It is not right to go on guessing more!
You should do the tests as requested / and follow up with your doctor...
Wishing you speedy recovery