Physicians rely on hemoglobin A1c (A1C), an integrated measure of glycemia (blood glucose), to make treatment decisions for patients with diabetes. There is evidence that, given comparable glycemia, A1C results in African Americans can be significantly higher than in whites with similar mean glucose. Racial differences in glycosylation (and thus differences in A1c results) could lead to inequities in diabetes diagnosis, performance measures (e.g., HEDIS), treatment (e.g., unnecessary treatment intensification), and hypoglycemia risk. It is unknown how the A1C-glucose relationship varies in other groups, e.g., Latinx or Asians. Further, it is unclear to what extent observed racial differences may be attributable to innate physiologic factors (e.g., sickle cell trait) or socioeconomics for which race may be a surrogate. We propose to collect glucose data from continuous glucose monitoring (CGM) devices and compare them to A1C data to better understand racial biases in the A1C-glucose relationship.