Wow...there are a lot of people commenting here that clearly have no idea what they are talking about.
First off, let me say that everything I post here is for the US...I don't know anything about the laws in other countries.
First off...in regards to SureScripts...while they would really like you to believe their claims...they just aren't true...at least at this point. As far as I am aware, the only way for a doctor to access information in SureScripts' system is by going through a state-run program which has access to it - an to date, only 1 state does this...and they are getting about a 75% success rate.
Now, in regards to HIPAA...everyone thinks that HIPAA does much more than it really does. HIPAA allows any healthcare professional (doctor, nurse, pharmacist, etc) to share your information with any other healthcare professional which has a medical interest in your information. It also allows them to share your information with law enforcement should they believe that you have violated the law. Also, HIPAA only covers certain entities...government agencies, in general, are not covered by HIPAA.
Now, to address the original question, the answer is, it depends on where you live. Many states have state-run Prescription Monitoring Programs (also called PMP or PDMP). Each state's laws are slightly different, meaning who has access to the information is different, how they access it is different, when they can access it is different, and what information is available is different. See
http://www.nascsa.org/rxmonitoringnascsa.htm for more information, including which states have PMP's and their contact information.
I have never heard of a doctor calling an insurance company for this information, although I wouldn't rule it out. In most states, a doctor can call a pharmacy directly and ask for the information, though.