This measure examines changes in Hemoglobin A1c using 3 Performance Rates: Performance Rate 1: The percentage of patients aged 18-75 years whose most recent Hemoglobin A1c has decreased by at least 1% from the highest level to the most recent level out of all patients with at least 2 Hemoglobin A1c levels in the measurement year or year prior to the measurement year with at least one Hemgolobin A1c greater than or equal to 9%. Performance rate 2: The percentage of patients aged 18-75 years whose most recent Hemoglobin A1c has increased by at least 1% from the lowest level to the most Hemoglobin A1c, out of all patients with at least 2 Hemoglobin A1c levels in the measurement year or year prior to the measurement year with at least one Hemoglobin A1c less than 9%. Performance Rate 3: The difference between Performance Rate 1 and Performance Rate 2, divided by the total denominator. Performance Rate 3 is the final performance rate for this measure.