The painkiller tramadol (brand names Ultram, ConZip, Ultram ER) is linked to an increased risk of hospitalization for hypoglycemia (low blood sugar) in people both with and without diabetes, according to a recent study by scientists at McGill University in Montreal. The use of this medicine has grown in recent years, with retailers dispensing 43.8 million tramadol prescriptions in the United States in 2013.