Getting a snapshot of your body's ability to metabolize carbohydrates is a much more granular view into metabolic health than are 'summary statistics' like A1C. Continuous glucose monitors, like those by Dexcom, are especially valuable -- you can get a detailed characterization of insulin response to food, of energy mobilization during exercise of different intensities, of general systemic stress, etc.

People are coming around on glucose in the same way that we now understand that the cardio signal (preferably using a sensitive measure like ECG, but even with crappy PPG sensors) are predictive of an enormous number of physiological and psychological phenomena.