It may be an urban legend, but I have heard that potatoes in Ireland are so sweet that diabetics are advised to avoid them.
They're not sweet like sugar, but there's an underlying sweetness that's part of their deliciousness.
The first potatoes in Ireland were called "An Spáinneach Geal", or "The Bright Spaniard"; we have always grown them in the same style as the Peruvians - the duplicitously-named lazy-beds formed by making a ridge a metre wide, putting the potatoes in rows along it and folding and earthing up on top, continuing to do so as the leaves grow, to make a long stem that produces many tubers along its length.
Some recipes here.