Diagnostic Innovation Testing and Knowledge Advancement Act of 2013 - Sets forth additional factors for the Secretary of Health and Human Services (HHS) to consider in determining the payment amount for new clinical diagnostic laboratory tests under gapfilling procedures which are used when no comparable existing test is available.

Directs the Secretary to convene an independent advisory panel to inform and make recommendations to the Secretary regarding any new test.

Requires the Secretary to justify publicly the basis and rate determination for any payments made under the clinical laboratory fee schedule for new clinical diagnostic laboratory tests, including a detailed summary of information received regarding the additional factors considered.

Requires the Secretary then, after publishing such justification, to provide for a reasonable period of reconsideration to: (1) receive any appeal of the payment determination, and (2) evaluate any additional information received regarding the justification and the factors considered.

Requires the Secretary, following the period of reconsideration, to make a final payment basis and payment rate determination, providing a justification for it with an explanation of what additional information was evaluated during reconsideration and how it was taken into account.

Directs the Secretary to: (1) establish a process for application for the assignment of a temporary national HCPCS (Healthcare Common Procedure Coding System) code to uniquely identify a diagnostic test until a permanent national HCPCS code is available for assignment to that test, (2) analyze the process used for the gapfilling procedures used in determining payment amounts for new clinical diagnostic laboratory tests, and (3) implement improvements in the process after public notice and opportunity for comment.

Applies this Act to payment basis and payment rate determinations made on or after January 1, 2013.