Can one have cushing's syndrome for the past 10years and not know about it? would the symptoms be mild/slowly progressing all the while?

10 years: That would be extremely unusual! Has your doctor told you that you have Cushing's? Has anything been done about it?

Cushing's: Sometimes Cushing's comes on fast, but sometimes it can be present for years before it is diagnosed. The symptoms of Cushings, central obesity, diabetes, hypertension, are very common. Raising suspicion for Cushings is abdominal striae, bruising, hirsutism, low potassium, rapid onset, and others. The screening tests for Cushings are fairly easy to do.