Are there people who are sugar intolerant?

Since birth, I haven't been able to eat sweets. If I do eat them, I become nauseated, weak, and hypoglycemic. I also can't eat fruits, lots of vegetables, or sweeteners. I can taste the smallest amount of sugar in a food. The weird thing is, I love pixie stix, gobstoppers, and sweettarts. My brother is exactly like me, so I know I'm not the only person out there. Most people just think we're crazy. What is this?