First, run to Walmart, and get a blood
glucose meter so he can test daily at home. Without one, you're flying blind. Then until you can read up on low carb food preparation, cut all of the "white foods"; not reduce, cut! That means sugar, pasta, rice, potatoes of any kind, any starchy foods. If your grandfather is ambulatory, even a small walk is beneficial in reducing blood glucose levels. Kepp testing everyday, and with no cheating hopefully he'll see the levels decline.