One size doesn’t fit all. Doctors often use AC1 tests, which provide a three-month average of a patient’s blood sugar, to diagnose and manage diabetes. But a new report warns that the test can be wildly inaccurate for those carrying the sickle cell trait — which 8 to 10 percent of Black patients do. After correcting for bias, the number of sickle cell trait carriers diagnosed with diabetes nearly doubled. That margin of error doesn’t just affect individual treatment, but calls attention to diversity concerns in medical research.