The Alcohol smell could or could not mean a person has been drinking.
Adult Onset Diabetes shows up gradually in older, usually heavier people.
Even though they have passed their last FAA exam, it is possible that the pancreas has slowed enough so they have diabetes.
If a diabetec consumes starches, they can ferment and form alcohol in the body. This is a well known problem for police who are stopping drunken drivers. In this country they have to discertain whether the drive is a diabetic or not.
It has also been the subject of many movies.
This is why we have to undergo the six month exam (at least for Captains in my country).