I'm worried and I don't know what I should do...

So, I am a 32, almost 33, year old white male, overweight and not in shape, but for pretty much as long as I have lived, I have been "not diabetic". My family has a history of diabetes, but usually at the older ages, like grandparents. No one else has it family-wise.

Just yesterday, my girlfriend (who is a Type 1 herself) noticed that I have been frequently urinating and drinking a lot (usually water, but some Diet Pepsi as well), more than usual. I had noticed it when she mentioned it as I downed a 1L of Aquafina in about 30 minutes. Since these are the signs of her being high with her diabetes, she decided to test my sugars last night before bed, and I found out it was about 13, pretty high for a non-diabetic. We went to sleep and I was then checked again for my "fasting sugars" and that was around 10, which is still high. So I decided to try and control my eating, like definitely not touching any junk food to start and really controlling my portions, but when I just checked my sugars again, now they're 17.

As for my A1C, I had it checked several months ago and was found out to be 6.1, which is "pre-diabetic". I'm going to be getting it checked again very soon, and I'm hoping it hasn't climbed higher but I am expecting it to have done so.

I'm just worried now that my blood sugar seems to be out of control and I can't seem to get it to lower, and if I eat anything it's just going to shoot up like a rocket. And being "non-diabetic" still, I'm not really sure I can just borrow insulin from my GF and start injecting it in the hopes that it will keep it under control. So I'm wondering if anyone knows what I can try to do, besides diet and exercise, that I can try to get things under control and hopefully prevent myself from becoming diabetic? Not looking for any "miracle cures" or anything like that, just hopefully some extra steps I can take to bring things down to normal, if possible.