Hi,
Diet has been shown as a factor that aggravates acne especially high glycaemic index food and excessive dairy products. However, diet per se has not been shown to improve oily and acne-prone skin.
There are effective medication that will help prevent acne in oily and acne-prone skin especially the topical retinoids (tretinoin and adapalene). These are prescription medication that your doctor can prescribe to you based on your suitability and tolerability.
Coupled with a healthy diet avoiding high glycaemic index food and excessive dairy intake, you will be able to minimize comedone formation and acne outbreak.
Hope this helps!