I feel that am not satisfying sexual needs of my wife. Iam in 40's and am diabetic and that must be the reason. I do not want to go for any viagra or oral treatment. Please advise.

How are your energy levels and have you been to the doctor and mentioned to them about this? Karma Sutra is really good. Raw food diets are good for diabetics in stabilizing insulin. So, you can discuss with your doctor about that.