I've just started using Freestyle Libre[1]. It's quite affordable even though it's not as accurate as blood measurements. It's possible to have one sensor attached for up to two weeks. This should be enough time to assess your body's reaction to carbs.
I don't know how you would test for pre-diabetes but to test for diabetes you can basically just drink a lot of sugar-water and see what your blood does. There are levels you can't reach unless you're diabetic.
Personally I've switched to a mostly carb-free diet because managing sugar levels is much easier that way.
[1] http://www.diabetes.co.uk/blood-glucose-meters/abbott-freest...
The development of xDrip plus is very active, so you probably want to use the nightlies.
Taking the measurement by washing your hands or wiping off your finger with an alcohol wipe, let dry, prick finger, squeeze to produce a small blood droplet, touch the end of the strip to the blood.
As far as interpreting expected results an hour after a meal; it depends on about a half dozen primary factors.
- Baseline fasting glucose level - # of carbs consumed - Ratio of simple/complex carbs and how much associated protein and fat in the meal
8 carbs of juice will spike blood sugar a lot faster than 8 carbs of ice cream because fat/protein/fiber can all slow down absorption of the carbs.
But in general healthy glucose level is 90 - 120 mg/dL and I'd imagine an hour after eating you should be a bit higher maybe up to 140.
Yes, it's doable with over-the-counter products. You need a meter and lancet device, and then for each test, a single-use lancet insert (tiny needle) and test strip.
These are usually bundled together in a pharmacy for $25-$75. However, if you look or ask the pharmacist, there's often a 100% money back refund right in the store.
Additional test strips are $0.75-$1.75/strip in packs of 25, 50, or 100. While that sounds expensive (and for diabetics, is), for the purposes we're talking about, one could probably only test after high-carb meals and a few days of fasting readings. The included 25-50 test strips may yield enough data to act on, and if not, one more 25-50 pack probably would.
https://www.diabetesselfmanagement.com/blog/what-is-a-normal... has more about when to test (basically, 1 and 2 hours after the start of a meal) and what results to expect. Feel free to ask the pharmacist to show you how to use it and interpret the results.
Important note: this feels nothing like a blood draw. It's barely noticeable at all and not anything I'd call painful. There's a depth adjustment on the lancet, so it's the tiniest imaginable prick on the side of a finger. It yields less than a drop of blood, then immediately closes, ie, no bandage or bleeding.
I did this myself as an extension of quantified self in 2012 (https://twitter.com/troyd/status/281931325471068161), just because I wanted to see the readings and the process. I did it again this year to see whether the testing process had improved (no) or my results had changed (no). Other than some puzzled pharmacists who aren't used to people buying a meter for cash, there's really nothing to it. It'll also give a tiny peek at a process that millions of people do all the time.
It's fascinating to see how one's body responds, particularly to meals that aren't obviously unhealthy (and depending on the person, may not be). Some examples: sandwiches (especially on big hoagie/grinder-style refined bread), burritos (tortilla+rice+beans), any meals with 2 significant sources of carbs (sandwich with fries or potato, breakfast with toast and hash browns, etc), and pasta. These aren't inherently unhealthy, but they all significantly raise blood glucose, and the only way to see how much is to test. More on "glycemic load": https://www.google.com/search?q=glycemic+load
Thank you for taking the time to write out your comment, I will be buying the testing supplies in the coming days.