any advice for a diabetes 2 sufferer

not me, but my older brother...
plus he has a lower disc back injury
he has professionals advising him...but but but

he is using the fish oils, and glucasamine for his back pain..which appears to be helping him...

he also likes a bottle of red a day
and trys to stay within a diet... rides a bike, and goes to the gym
but I suspect he cheats on chocolates and sweets
he is having a load of trouble with his feet...his big toes
he weighs around 115 kg...he did diet and dropped to 80 kg..but put it back on again...he is a 6 footer and a big bloke

he lives alone....is a good cook, and retired
I think it must be very difficult for him to adapt to this retirement style lifestyle
he is active in the garden, and will do anything for everyone...
he was on a mainly fish, seafood and salad diet... so I dont get it, how he has put on so much weight...

I would hate to go thru what he has to...on a daily basis

If you can help, please put it in simple laymans terms, we are not scientifically minded, and possibly brain dead with regards to medical terminology.
cheers