What Causes Flushes At Night?

I am a 73 year old male and the problem i am having is flushes/sweats for the past 8years. Moderate during the day but very heavy at night. I have type 2 diabetes and have been consulting with my G.P. about these sweats. He is sure there is no link and has done so many blood tests and can come up with no answer to this. They are really effecting my mood and sleep and starting to really get me down. Apart from this I am healthy and play golf so I do get regular exercise. I would be grateful if you have any advise on this. Thank you