Is there treatment needed for glaucoma suspect, or only after being diagnosed with real glaucoma?

Careful observation. The suspicion for glaucoma implies that your optic nerve has some borderline features that may require treatment if other factors change, such as increasing iop, large iop swings, changes that may be evident in diagnostic testing such as optical coherence tomography or visual field testing. A thin corneal thickness and positive family history of glaucoma will also play a role in treatment decision.
Glaucoma suspect. General health measures....Monitor your blood pressure, get checked for diabetes and any hyperlipidemia...But the most important measure you can take is maintain periodic eye exams 1-2x per year.