When it comes to diabetes, there is no one size fits all answer. What works for one diabetic may not work for the next.
Best thing to do is for you to get a blood glucose meter if you do not have one already.
Try out one food at a time - in this case potatoes. Log everything that you eat. Test 2 hours after eating. If you are under 140mg/7.8 mm/ol, then you are OK. If you are above this target, then you need to look at what you ate. Either reduce the portion, or cut it out entirely.
Everyone's body is different. Only by testing will you find patterns that are right for YOU, and only by testing will you know how much of each food, you can eat.
In general many diabetics find it hard to eat potatoes because they are so high in carbohydrate and hence spike their blood sugar. But YOU have to find the solution that is right for YOU and you alone.
BTW also note that you will probably react to potatoes differently depending on how they are cooked. You should do your own blood sugar experiments with various styles. For example I know that my body reacts slightly differently to low fat high carb potatoes (boiled) compared to high fat high carb potatoes (French fries).