Why not tell us what you would recommend for a non-diabetic client (and why) and we can then suggest what (if any) might be inappropriate for a diabetic.
Diet before exercise may also be a useful topic - for instance there may be things a T2 can eat before exercise (and also you need to state how much exercise) which would be inappropriate at other times.
For example, a medium distance run (6 miles+) might be a chance to eat a Mars Bar cut up into sections without the usual dire consequences.
One interesting aspect of diabetes and exercise; as I understand it, normally you would not eat high sugar foods such as a Mars Bar before exercise because the sugar rush is countered by an increase in Insulin which then clears the sugar out of the blood stream leading to reduced blood sugar which is then taken low by the demands of exercise (peak then trough) which does not give you long term stamina.
This is why slower release foods such as malt loaf have been recommended to provide fuel for long duration exercise such as cycling and distance running.
However if your Insulin response is not rapid and you do not flush the sugars out of your blood stream (as with a lot of T2 diabetics) then you may get a longer term energy benefit from taking in sugars before and during exercise. All the sugars go to the muscles to be burnt. It obviously needs careful management to make sure your blood glucose levels are not taken too high.
Have you looked at
www.runsweet.com?
Although primarily aimed at T1 diabetics it is a good general resource for exercising diabetics in general.
HTH
LGC