Having to deal with your glasses slipping down your nose can be really annoying. If your nose is oily or if you're exercising and sweaty, you probably have to adjust your glasses very frequently. It doesn't take excessive oiliness or sweating to make your glasses slip. I can't advise you whether your skin is too oily or whether you're sweating too much, that's a dermatological diagnosis you're going to have to make together with your doctor. What I can offer are some tips on how to keep your glasses in place on your face.