The IDF Diabetes Atlas has a number of peer-reviewed publications associated with it describing the methodology and results of major findings. Those publications can be found by following the links below.
The paper providing the new estimates of diabetes prevalence in adults with the source paper citations is available here
The paper describing the methodology is available here
Publications are available from Diabetes Research and Clinical Practice
The background papers produced as detailed explanations to the methodology used in the 4th edition of the IDF Diabetes Atlas are also available here. Where the methodology has been changed for the 5th edition, please refer to the peer-reviewed publications listed above.