Hi Masi,
Did they base the diagnosis on your fasting bloodglucose alone? And on just one prick? Because I'd call that irresponsible doctoring. Everyone experiences "dawn phenomenon", when your liver dumps glucose into your system to give you energy to start the day. Did you ride a bike to the appointment? That could've raised your bloodsugars after all. What you really want to know is how your body deals with food. And you can do that with a meter. Here, people use meters that are readily available in the UK. Most Dutch pharmacies only have a Contour by Bayer or something similar, so you'll have to decide where you want to get your strips from. Do you want to walk into any pharmacy and be able to pick some up, or are you willing to wait a while and order online? In any case, yeah, most meters have a 15% deviation/margin of error, but that's still enough to let you know where you stand. Because frankly, with your hight, weight and age, I wouldn't expect prediabetes (which is an early indicator of an approaching T2 thing). T1's don't make any insulin. A T2 makes loads of the stuff, and has thus become insensitive to it. One of the symptoms of that is weight gain. Not a problem your dad would have, so yeah, he's not likely to be overweight. In any case... Once you get a meter, test before a meal and 2 hours after the first bite. If your BG doesn't go up more than 2.0 mmol/l from where you started, that's wonderful. if it does but is still within the non-diabetc range, that's quite wonderful too. In the meantime though, you might want to go back to your doctor and ask for a HbA1c test. That's the average of 3 months worth of bloodglucose. That will tell you right quick whether you truly are prediabetic, because one test in the a.m... Is quite inconclusive. I'd be more worried if you were seeing 8's or 9's in the morning, actually.
You know what, get the HbA1c done first, before you shell out on a meter. (They're not expensive, but they only come with 10 test strips. And the strips are the money pit). The HbA1c is covered by your insurance, so shouldn't be a problem. Testresults come in in a day, maybe two, depending on whether you get the blood drawn right by the hospital's lab or elsewhere at a different "prikpost".
As for what constitutes a good diet, that's a discussion for another day, (De Schijf van Vijf/EatWell plate is a load of ****, sadly) but as for your original questions... Yeah, Pepsi Max, once in a while, is fine.
Whatever the outcome of the HbA1c, you're going to be fine. Loads of info here, and hope too.
Groetjes,
José