A new study published in JAMA Internal Medicine has found that the popular mild opioid tramadol is linked to high rates of hospitalization for hypoglycemia (dangerously low blood sugar.) In the case-control study, the use of tramadol was associated with a 52 percent higher risk of hospitalization for hypoglycemia compared with codeine. The risk was highest during the first 30 days of use, about three times as high as codeine. Tramadol is seen as a lower-risk alternative to other opioids and its prescriptions have increased in recent years. In August, the opioid became a schedule IV controlled substance. The researchers, who hail from McGill University in Montreal, wrote that three recent case reports have described tramadol-induced hypoglycemia, which included patients with and without diabetes who used the drug at recommended doses.