Poor numeracy: the elephant in the diabetes technology room.

For people living with type 1 diabetes, the Holy Grail of a closed-loop artificial system, combining glucose measurement and insulin delivery without requiring input from the individual with the condition, remains elusive.1 At present, the optimum approach appears to be a combination of insulin pump therapy and real-time continuous glucose monitoring.2 However, despite patient acceptance of this technological approach to glucose control,3 the majority of people still continue to use multiple daily injections (MDIs) of insulin. Whatever the method of insulin delivery, a fundamental component of training in intensive insulin therapy requires participants to be adept at handling numbers in order for them to understand the nuances of glucose monitoring and to calculate appropriate and safe insulin doses (Table 1).