High voltage ripples at the output, high peak current in semiconductors (switch & Free wheel diode), higher flux density (or conversely larger physical size) in inductance.

I want to add one more point to Sujit sir's answer. After having above all disadvantages, DCM is mostly used in low power converter circuits only.

in real time does it effect the life time of the components?

If the components are selected for the higher current peak, there is no early failure. Note that the output filter capacitor must also be rated to handle the higher ripple currents through it, which are generated by the higher ripple voltage across it.

@ sujit sir   there is no early failure ....means?

If the converter is designed to operate in CCM with optimum components designed for the purpose, and if the same converter is subjected to operate in DCM obviously there is early failure of components due large stress as told by Sujit sir