how to know datatypes

Question

I have an excel sheet which I am trying to read with c# and ado.net using a OleDbDatareader. The problem is that the data is not consistent within the columns so I can't just always use getstring or getint etc. I tried getvalue but that returns a null or empty string when the datatype of the column changes. Is there any trick to doing this as its getting frustrating for something that seems like it shoudl be so simple. Thanks in advance Lorne