You can extract the data from an excel file (without opening it) and use it inside an AutoCAD file for drawing objects;
This is just an example on How to use the data from Excel Cells inside the CAD drawing to Automate the Autocad drawing process.
Don't forget to add Microsoft Excel Object Libraries (Tools->References) [AutoCAD VBA Editor]
Create Custom Commands for Excel - VBA
You can create Custom Commands for Excel to perform some predetermined operations. These commands can be entered directly inside a cell to do the required actions (calculations)
Please note that, these commands are made on VBA, so please refer our previous articles for the basic idea on Macros and VBA
Example Command : ADD
Command to ADD to values from columns A and B and display in C, the command “ADD” will be typed in cells of Column C