Shelley...

Low carbing does not ruin your metabolism unless you are yo-yo dieting (going on and off low carb, losing and regaining the weight) or trying to follow a very low calorie (VLC) version of it. VLC diets, whether they are low carb or not will wreck your metabolism.
I have diabetes which is insulin resistance gone extreme and low carbing has basically reversed it.
Your friend's doctor may know a lot about her and her other conditions, but they don't know a lot about low carbing and insulin resistance based on what they told your friend (Atkins causing insulin resistance). How interesting that in the next breath they recommended a low carb eating plan. Perhaps they think that Atkins is nothing more than induction levels of carbs for life in which case, they really need to read the whole book. Or perhaps they're basing their opinion on seeing patients who try to follow the Atkins plan without ever reading the book and do it all wrong.
If a doctor told me that low carbing causes insulin resistance (knowing what I know now) I'd be running for the nearest exit and not looking back.