Re: Potentially stupid questions
"Die-gan" (with a hard G) is my first instinct too, but I'm in the country immediately south of Canada (since I read today that some people in Latin and South America resent people from a certain country in North America calling themselves "Americans"), so maybe pronunciation is different.
If you're really in doubt, you could try writing the author to ask.
Dr. Howard, Dr. Fine, Dr. Howard: For Duty and Humanity!
--Men in Black, 1934.