Can I low carb diet if I'm diabetic or pre-diabetic?

A low carb nutritional program is ideal for type2 diabetics. (Type1 diabetics should investigate Dr. Bernstein's site, and consult with their health care providers.) The more restricted carbohydrate intake is, the lower one's blood glucose levels will be.  

Dr. Atkins did, and Dr. Bernstein still does, treat diabetic patients with very restricted carbohydrate intake being the very first measure. Many have found that their need for insulin and/or oral hypoglycemics are eliminated or greatly reduced when they follow a truly low carb way of eating. For that reason it is very, VERY important to work closely with your health care provider to monitor your changing medicinal needs, since a quick drop in blood sugar can be a very dangerous event