My neighbor says that since I have tingly left arm that I may have diabetes. Occasionally I have blurred vison?

Possibly, see a MD. Diabetes usually causes tingling in both hands/feet, but it can begin on one side. It can also cause mononeuritis, inflammation of a single nerve and this may be your problem. Changes in blurred vision can be due to swelling of the lens as the blood sugar goes up and down. Your doctor can check your blood sugar and hemoglobina1c levels as well as other tests to figure out the tingling.
Not necessarily. What you are describing could be an isolated neurological finding, however, i urge you to discuss with your physician asap since medical testing seems to be needed (such as emg, a1c, thyroid testing, b12/folate levels, etc). Hope it turns out to be of transient nature.