I've gotten some directly from walmart.com in the past with no prescription. There're a lot of other options lately, like agelessrx.com, levelshealth.com, Veri, Nutrisense, January.ai.
It may give you some life changing insights. Oversimplified, high glucose spikes = shorter life. And it's not a simple issue of carb intake. Your behavior, personal biology and dietary environment (fat? fiber? protein? stress? food sequence?) yield huge variation.
If you decide to learn more about this subject, Peter Attia is a great (if involved) start:
https://peterattiamd.com/?s=insulin
Within a couple days I learned things like I was hypoglycemic during sleep, and my daily oat milk lattes were like eating candy (maltose), whereas an outrageous French dinner left me totally level (fiber/fat).