Dear TKK,
I was exactly like you, and went to my Doctor. The feeling of being miserable and out of sorts with a lowering libido which was coincidental with the onset of my diabetes. He started me on Viagra but that did not help. He eventually referred me to the Andrology Clinic at the local hospital where they put me on Testosterone replacement. Magic! I felt happier, more energy, my BG reduced (slightly) and my wife started smiling too. On my follow up I said that I was feeling much better than I had for years and that I really did not realise how miserable I had been. The nurse said 'I bet you didn't realise how miserable you were probably making other people feel too', and how right he was. I feel ten years younger, so very good luck with your treatment. I hope you get as much benefit as me. Oh, and in my mind, there is definitely a link between diabetes and low testosterone.
Best
Hawkeye