I have read in various places that it can be insulogenic so best avoided. But would suggest trying and see if your husband is feeling brave. Why would you want it though?
He's 72 BB, and he too is a biker. He's finding the bike heavier and is losing some strength in his legs, getting a wee bit frailer. He doesn't eat a lot and is underweight, so I just thought of trying one protein shake a day to help him keep muscle. I am googling all about it but it doesn't have any info on diabetics.
As we age our bodys become less efficent at metabolising protein but it is better to get a little extra by eating whole natural foods. I increased my protein levels just by having more red meat during the week and having an extra few boiled eggs. More cheese didn't hurt either!
Edited to add. There is emerging evidence that suggests that protein is more efficiently metabolised in the morning rather than in the evening.
I Drink Optimum nutrition's Hydro whey 100% Sugar free and 95% Isolate protein. there are some other why you can try but check the level is they are sugar free.