(Concern) Is it because my blood sugar level is high?

I have a certain amount of sugar. However, I am not a diabetic patient. They say I am somewhat borderline. I also really like sweet foods.

A few years ago, yellow lines started to appear on my toes. I looked it up on the internet and found that this phenomenon occurs when blood sugar levels are high. However, my blood sugar levels are not that high.

Nevertheless, since these symptoms do not improve easily, I am worried. It could be athlete's foot, so I tried applying antifungal ointment, but it has little effect. Therefore, I thought there was no cause other than diabetes.

I'd rather have athlete's foot. It must be athlete's foot, right?