I have an autoimmune disease and as a result, I have frequent outbreaks seven years later on acyclovir. Another woman wrote that she had lupus and when her husband infected her, she ended up in the hospital. I suggest your friend finds a treating physician with experience in treating patients with Type 2 diabetes and herpes before he gambles with his health. As the population ages, there must be persons with both. It took a few doctors before someone recognized that I had a weakened immune system causing the frequent outbreaks.

Unfortunately, there is no 100% protection against herpes. According to an article in the New York Times, http://consults.blogs.nytimes.com/2010/06/18/giving-your-partner-herpes/, a condom alone is roughly 30% effective. Antiviral drugs alone are roughly 49% effective. Using both methods provide more protection; but not close enough to 100% effective. I know that the virus is transferred to uninfected partners 70% of the time without any symptoms (asymptomatic shedding) of an outbreak.

I think it's great that you are concerned for your partner's health. Good luck to you.