One fig is likely harmless. But an excess of anything is harmful. Limiting yourself to moderate amounts of good quality food generally and specific foods in particular, is the key to healthy eating.
Figs are very rich (and sweet due to their high sugar content, so they're not a great choice for diabetics except sparingly, say, not more than 2 or 3 per day). They're tasty and have a good fiber content.
Anything that raises blood sugar can be harmful. Please read Dr Richard Bernstein the diabetes solution. It will change your life. You don't have to follow him exactly but you can learn the tools for REAL CONTROL
Is eating xyz OK for a diabetic. ONLY way to tell is by testing. Why? every one is different what I can eat may make you go high... so, google "eat to your meter"
Figs are a healthy food, particularly the fresh type for people who are not diabetic. For people who are diabetic fruits should be very limited to help control blood sugars.