An infusion system for providing therapy modification, the system comprising: a glucose sensor system configured to obtain a measured blood glucose value; a controller operationally connected with the glucose sensor system; an insulin delivery system operationally connected with the controller; wherein the controller is configured to compare the measured blood glucose value to a target blood glucose value, and adjust a basal rate if the target blood glucose value is not achieved or maintained, wherein the adjusted basal rate is limited to be within a boundary wherein the boundary includes a maximum basal rate set as a percentage of a preset basal rate above the preset basal rate, and a minimum basal rate; wherein the controller is further configured to perform a safety action if the adjusted basal rate exceeds the boundary; wherein the controller is further configured to command the insulin delivery system to deliver therapy at the adjusted basal rate if the adjusted basal rate is within the boundary and, if the adjusted basal rate exceeds the boundary, the safety action ensures that the glucose history is not too variable for a therapy modification to be made and the therapy modification is only made if there is a consistent pattern in the blood glucose history, characterized in that the minimum basal rate is set as a percentage of a preset basal rate below the preset basal rate, and the variability of the glucose history is determined by using a standard deviation of a cluster of the most recent data and comparing this standard deviation against the difference between an average blood glucose value and the target blood glucose value. a glucose sensor system configured to obtain a measured blood glucose value; a controller operationally connected with the glucose sensor system; an insulin delivery system operationally connected with the controller; wherein the controller is configured to compare the measured blood glucose value to a target blood glucose value, and adjust a basal rate if the target blood glucose value is not achieved or maintained, wherein the adjusted basal rate is limited to be within a boundary wherein the boundary includes a maximum basal rate set as a percentage of a preset basal rate above the preset basal rate, and a minimum basal rate; wherein the controller is further configured to perform a safety action if the adjusted basal rate exceeds the boundary; wherein the controller is further configured to command the insulin delivery system to deliver therapy at the adjusted basal rate if the adjusted basal rate is within the boundary and, if the adjusted basal rate exceeds the boundary, the safety action ensures that the glucose history is not too variable for a therapy modification to be made and the therapy modification is only made if there is a consistent pattern in the blood glucose history, characterized in that the minimum basal rate is set as a percentage of a preset basal rate below the preset basal rate, and the variability of the glucose history is determined by using a standard deviation of a cluster of the most recent data and comparing this standard deviation against the difference between an average blood glucose value and the target blood glucose value.