Lots of things can cause balanitis - lack of cleaning, irritation from harsh soaps, using a different kind of soap, skin conditions like psoriasis or eczema, etc.
Diabetes can contribute to balanitis, but pre-diabetes shouldn't, unless your blood sugar is regularly really high.
You need to make sure you are taking care of yourself. Eat well, use a gentle soap or non-soap cleanser, exercise, avoid alcohol, etc. I'm sure you know the drill.