THE GESTATIONAL DIABETIC
Overall, potatoes are high glycemic, except when cooked and cooled. Potatoes cooled and served cold are low glycemic.
Potatoes naturally contain resistant starches. Cooling potatoes increases resistant starch, thereby lowering the glycemic index.
When reheated, some of those resistant starches revert to starch, increasing the glycemic index.
The American Diabetes Association includes potatoes on their list of myths, noting that they don't need to be avoided but portioned.
As of now, cold potatoes are the lowest glycemic, but whether hot or cold, portioning is the key to incorporating them into your diet and balancing blood sugar.