Patients with abnormally high blood sugar levels are more than twice as likely to die from COVID-19, researchers in China said Saturday. It is the first time scientists have been able to confirm that patients with hyperglycemia, but not diagnosed with diabetes, are at higher risk of death from COVID-19, they wrote in the journal Diabetologia. The researchers examined death rates for 605 COVID-19 patients at two hospitals in Wuhan, China. Having high blood pressure is “independently associated” with increased risk of death and complications from COVID-19, they wrote. The study builds on previous research on diabetic patients. One-in-10 COVID-19 patients with diabetes died in French hospitals, a far higher proportion than for patients without the condition, a May study in the same journal found. Exactly why high blood sugar increases COVID-19 death rates remains clear. The authors of Friday’s study suggested that blood clotting, the weakening of blood vessel linings, and cytokine storm syndrome — an overreaction of the immune system — could all play a role.