This is a large scale study of children and adults with type 1 diabetes in the United States. Twenty-five thousand people have been enrolled and results have been published since 2013. A study of adults with type 1 diabetes of at least two years duration and not using continuous glucose monitoring compared those with excellent control (HbA1c <48, N=627) and fair/poor control (HbA1c >69, N=1267). Results showed that excellent control was associated with higher socioeconomic status; being older and married; not being overweight; frequent exercise; lower total daily insulin dose per kg; more frequent monitoring of blood glucose; administering mealtime boluses prior to rather than at or after eating; monitoring before giving a bolus and missing an insulin dose less frequently. Frequency of severe hypoglycaemia was similar for both groups but diabetic ketoacidosis was more common for those with poorer control (Simmons et al 2013).