Continuous
glucose monitoring (CGM) provides comprehensive assessment of daily glucose measurements
for patients with diabetes and can reveal high and low blood glucose values that
may occur even when a patient’s A1C is adequately controlled. Among the measures
captured by CGM, the percentage of time in the target glycemic range, or “time
in range,” (typically 70–180 mg/dL) has emerged as one of the strongest
indicators of good glycemic control. This review examines the shift to using
CGM to assess glycemic control and guide diabetes treatment decisions, with a
focus on time in range as the key metric of glycemic control.