For two years, Rosemary McGinn’s friends and family were convinced she was perpetually intoxicated. But instead, McGinn, 53, suffered from insulinoma, a rare pancreatic tumor that constantly produces insulin, even when blood sugar is low. Insulin is a hormone that causes cells to absorb glucose from the blood. With insulin continuously streaming through her body, McGinn’s blood sugar would drop to dangerously low levels. “When my sugar would suddenly crash, it was like I was drunk,” McGinn, from Rockland County, NY, told Fox News. “I would become very combative, not knowing what I was saying and sway back and forth.” Normal blood sugar is around 100 milligrams/deciliter for most people, says Dr. Ronald Tamler, clinical director of the Mount Sinai Diabetes center, who treated McGinn. "Most people start feeling poorly when their sugar dips below 70,” says Tamler. “But Rosemary had a sugar of 20. That level usually leads to seizures and coma.” Mount Sinai performed a 90-minute surgery to remove the tumor, and McGinn’s symptoms subsequently disappeared. Dr. Tamler froze the tumor and added it to Mount Sinai’s database of tissue samples, in the hopes that it will help doctors to understand the mechanisms that control blood sugar. According to the National Diabetes Foundation, 8.3% of America’s population is diabetic.