OBJECTIVES: Recent studies using continuous glucose monitors (CGMs) in T1D produce multiple daily readings used to define a novel construct called time in range (TIR; sanctioned by the International Consensus on TIR Targets, 2/2019), optimally between 70 mg/dl and 180 mg/dl. Multiple readings allow for calculation of a %TIR that has been linked to HbA_1c improvements, greater risk for severe hypoglycemia (SH) <54 mg/dl, and diabetic ketoacidosis (DKA) >270 mg/dl. A COA was performed comparing clinical cost offsets for two CGM systems (rt-CGM and is-CGM) in T1D subjects (n=2,000) with impaired awareness of hypoglycemia (IAH; ~30% of T1D) applied to eight countries over a one-year period. METHODS: Clinical effects included %TIR (Reddy, 2017) for glucose as a proxy HbA_1c measure (algorithm from Beck, 2019), reduced hospitalizations for SH and DKA (Charleer, 2018) based on %time spent in low and high glucose ranges (Reddy, 2017), respectively. Costs attributable to HbA_1c reduction, SH and DKA hospitalizations were taken from country-specific published literature and inflated to 2019 values. RESULTS: RT-CGM %TIR compared to is-CGM (Reddy, 2017) resulted in estimated HbA_1c reductions of -0.95% and -0.52%, respectively. The %time spent at low glucose (<54 mg/dl) between the groups yielded 132 fewer SH hospitalizations for rt-CGM. The %time spent at high glucose (>270 mg/dl) yielded one fewer DKA hospitalization for rt-CGM. Estimated annual cost offsets per T1D subject with IAH using rt-CGM over is-CGM is as follows: USA, $US 1,114; UK, £454; Spain, €494; France, €650; Italy, €655; Germany, €673; Canada, $CAN 703; Australia, $AUS 722. CONCLUSIONS: Recent RCTs comparing rt-CGM with is-CGM have demonstrated important differences in %time spent at low, optimal, and high glucose that are likely to translate into significant clinical and economic benefits for rt-CGM. The %TIR metric may grow in clinical significance as the relationship to HbA_1c is more fully described.