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). Table 1 Factors to be Taken into Consideration When Calculating a Mealtime Insulin Bolus In practical terms, “numeracy” is “the ability to understand and use numbers in daily life.”4 For individuals with type 1 diabetes using intensive insulin therapies, this skill requires them to be able to: Count Perform basic math functions (calculations) Use fractions, decimals, and percentages Understand graphs, tables, and measurements Decide when to use these skills (functional numeracy) Therefore, difficulty in handling numbers is very likely to impact negatively on a patient’s attempts to achieve optimum control of blood glucose levels. Difficulties in reading, writing, and listening will also have an influence on the ability of individuals to learn about diabetes and understand and manage the monitoring and treatment required of them on a daily basis. Unfortunately, educational material provided for patients with diabetes often has suboptimal readability, requiring literacy skills well above the average ability of many adults.5 In addition, although many patients may have adequate literacy ability, they still may lack skills in numeracy necessary for many health-related tasks. Inability to apply effective numeracy skills can also lead to considerable anxiety in the individuals and their families.6 In 2008 the U.K. House of Commons Public Accounts Committee reported, “that large numbers of the adult population of England are functionally illiterate and innumerate.”7 Similarly, in the United States, almost two in three adults cannot perform the most rudimentary of quantitative skills, and difficulties with numeracy may be an overlooked factor contributing to racial disparities in achieved glycemic control for people with diabetes.8 There is also an inverse association between numeracy (but not literacy) and body mass index, which has important implications for weight management programs that require participants to monitor calorie intake and energy expenditure.9 Poor numeracy has also been shown to have economic, social, and psychological impacts including higher rates of depression, low self-esteem, and the feeling of a lack of personal control.10 In employment, numeracy, even more than literacy, has a powerful effect on earnings. People with poor numeracy also tend to leave full-time education at the earliest opportunity and usually without establishing qualifications.11