My mom's
Doctors made this easy for me when she got lost in the middle of the night in a nearby town and ended up in the hospital. Her neurologist insisted she had to take a driver's test. Thank God she hasn't taken the test because we are afraid she might actually pass it, and that would make our lives Hell on so many levels. I just took her keys away on the advise of an attorney, and now she literally hates my guts. However, I have heard doctors rarely help unless they are pretty sure there is an issue. Still, you could bring up your concerns with his doctor.
Also, in some states, you can contact the DMV if you are worried about someone who should not be driving.
In her state (Indiana), you can go to the DMV and get a form expressing your concern about the driver in your family. They will call the person in for a test. It is anonymous. They won't tell the person who flagged them. Good luck!
It is a difficult move to make someone stop driving, as most people regard driving as a key to their independence. But it would be even more difficult to have to face having them involved in a terrible accident.

Several things made it easier for my husband to stop driving. Our grown son needed a car and since mine was new, we gave him my husband’s car. Also, my husband’s hearing loss is so severe, I told him I didn’t feel safe with him driving because he couldn’t hear and understand me. It’s difficult for them to give up that freedom, but he has adjusted.

Have your Dr. notify DMV.

Judy, if you believe your husband’s driving is a risk to himself or others, then you have to do something. I’ve seen plenty of folks here struggle with the same issue. It is massive in his life and yours, but safety must come first, not to mention that your husband’s insurance may be invalid if he drives while unfit due to illness. Best wishes in tackling this difficult issue.

I suggest you talk to his Doctor about his driving. My husband's Neurologist contacted the DMV and had his license revoked. This way he cannot blame you if he can no longer drive. It is really unsafe for him and for others on the road.