No prescription is required, but as the other comments say, you’re unlikely to learn anything significant.

Blood sugar in non-diabetics is boring, rarely moving in any significant way.

One impact could be dispelling misconceptions if you have them. Another could be discovering pre-diabetes.

> you’re unlikely to learn anything significant

This is simply not true and assumes all nondiabetics are current with their checkups and bloodwork. A third of all people are prediabetic and most of them don't know it. That's the opposite of unlikely.

Most start out nondiabetic (except type 1) and we live in a world with constant and significant cultural pressure guiding choices towards diabetes. Keeping an eye on it will catch when a nondiabetic is straying too far.

Glucose will still spike in nondiabetics when they mindlessly overindulge on carbs and can drop to borderline hypoglycemia when fasting for too long and/or overexerted. Tons of people take risks experimenting with "intermittent fasting" or other questionable diet choices. There are tons of people who incorrectly assume it's "just their mental health" and that there is no biological basis for feeling off until they have their A1C confirmed.

Even A1C can be misleading if there are nutritional deficiencies or the patient is type 1. You do not want to find out you're type 1 by surprise (passing out on a hot day in a traffic jam or something).