The correlation between coffee and blood sugar

I am a stroke patient and also have diabetes. After rehabilitation training at a rehab hospital, I was cured and am maintaining a normal life. However, I recently read an article suggesting that coffee is beneficial for blood sugar control. So I drink one cup of American coffee without cream and sugar every day. But another internet article says that coffee can raise blood sugar levels, so lately I have been almost quitting coffee. I also watch my diet carefully, which causes stress, and now adding coffee restrictions makes me more stressed. I wonder if milk coffee is harmful due to the added sugar, but I think plain American coffee might be fine. If anyone knows, please help me make a judgment.