Despite improvements for management of type 1 diabetes (T1D), patients have difficulty achieving glycated hemoglobin (A1c) levels recommended by the Diabetes Control and Complications Trial (DCCT). Two multicenter randomized trials were conducted to evaluate benefit of using a continuous glucose monitor (CGM) with standard glucose monitoring for T1D management. The primary study evaluated benefits of CGM in 322 patients with A1c >7.0 %. The secondary study evaluated 129 patients with A1c <7.0 %. In the primary study, CGM resulted in improvements in A1c at 6 m in subjects >25 years, but not those <25. However, all subjects using CGM regularly showed benefit. Improved A1c did not come with increased severe hypoglycemia as seen in the DCCT, and benefit was sustained over 1 year. In the secondary study, CGM use helped subjects maintain target A1c levels with reduced exposure to biochemical hypoglycemia. The data collected allowed for other analyses of important factors in T1D management.