Now, back to the question at hand. If you plan to use a duvet cover, then yes, you will need a duvet insert If you plan to use a duvet cover, then yes, you will need a duvet insert If you plan to use a duvet cover, then yes, you will need a duvet insert If you plan to use a duvet cover, then yes, you will need a duvet insertdo i need a duvet insert. Without an insert, a duvet cover would be like a hollow shell, devoid of the warmth and fluffiness that make this bedding option so appealing. The insert fills out the cover, giving it shape and providing the desired level of warmth.