My latest blood test showed a platelet count of 107 K/ul, and the normal range apparently is 142 to 328.  I dont believe I have any noticeable symptoms, although I have been a diabetic on relatively low levels of insulin for the last year.  Should I simply wait and see what the result is next year?
No, without any symptoms, this level is not worrisome. don't worry at all. Just wait and watch it will come back to normal. If any symptoms are that like bleeding or rashes then consult physician.