This study suggests that many patients on insulin pump therapy managed at a single specialty endocrinology clinic had some deficiency in DN skills. Although the median and mean DNT-15 scores were both reasonably high (93.3% and 87.5%, respectively), deficiencies in DN were still present. In addition, 19% of our patient population achieved a score of < 76%, indicating limited DN skills, which could have significant implications for the way in which they manage their insulin pump therapy. Importantly, almost one in five patients were unable to calculate the carbohydrate content of a food item when given a nutrition label—a task that insulin pump users should perform daily. Also, approximately one in five patients could not calculate an insulin bolus dose accounting for both carbohydrate intake and glucose level. This highlights a concern that some patients may be relying solely on the pump’s bolus dose calculator and are unable to perform dose calculations independently.
The occurrence and severity of low DN does seem to be better in our patient population compared to other studied populations. In a study conducted by Cavanaugh et al., the median DNT-15 score was 65% in a population of patients with type 1 or type 2 diabetes in either a primary care or diabetes clinic, which was significantly lower than the median DNT-15 score of 93.3% in our study population . This may be because our population was solely in a single, specialty endocrinology clinic and included patients with type 1 diabetes. In a study conducted by Zaugg et al., patients who received care from a specialist at a diabetes center had higher DN levels than patients who received care from a primary care provider, and patients with type 1 diabetes had higher DN levels compared to patients with type 2 diabetes .
This study also suggests that low diabetes-related DN skills may be associated with poorer glycemic control, as well as some worse perceived self-efficacy and self-management behaviors in patients on insulin pump therapy. Our findings are generally consistent with other studies that have shown similar associations in patients with diabetes [8, 10, 17], but, to our knowledge, our study is the first look into this potential association in patients specifically on insulin pump therapy.
Although one might speculate that patients with low DN would use an insulin pump differently than those with higher DN, we did not see trends indicating differences in pump-related self-management behaviors between DN groups. One interesting finding was that participants with high DN had greater use of manual boluses, which may indicate more comfort with performing dose calculations without the help of the pump’s bolus dose calculator.
This study also found that individuals who scored lower on the DNT-15 were older. Similar studies have associated lower DN levels with age [8, 10], indicating that as patients grow older their ability to effectively manage their diabetes may diminish. Additionally, older patients may pay less attention to serving size, thereby decreasing the accuracy of their nutrition calculations , which could increase the risk of administering an incorrect dose of insulin. Older patients are also at an increased risk of cognitive dysfunction , and are more likely to report worse adherence to diabetes care . Providers should recognize the impact that age may have on DN skills, diabetes self-management, and effective insulin pump use.
There are several limitations of our study. First, conducting the study at a single, academic, specialty endocrinology clinic limits the diversity of our patient population, so the findings may not be generalizable to a larger population. Several studies have indicated that low education level and minority populations have been associated with lower DN levels and poorer glycemic control [8, 21], but these populations were not well represented in this study. Of note, even though the participants in our study had high education levels, were mostly White, not Hispanic, and were generally well-managed patients under a high level of specialized care, low DN was still identified. This suggests that DN is a widespread issue that affects more than minority or underserved populations. Second, this study was designed as an exploratory, observational, cross-sectional survey that was performed to initially explore possible relationships, so no conclusions on causation can be made. Our study also had a small sample size, which limits the statistical analysis. Additionally, the DNT-15 includes several questions geared towards a more general diabetes population (e.g., those on insulin injections or oral medications), which could limit the validity of the tool in our patient population. Last, there was limited availability of self-management data based on the download capability of the insulin pump type and brand.
Our study reinforces the need to identify and address DN in the diabetes population. Health literacy and numeracy focused interventions and communication strategies have been developed for a more generalized diabetes population and have been shown to improve self-efficacy and diabetes self-management behaviors [22,23,24,25,26]. Such strategies should also be considered in patients on insulin pump therapy.
Adequate DN skills are crucial to patients’ ability to process and act on data related to their insulin pump . These requirements will expand as insulin pump technology continues to advance and with the incorporation of continuous glucose monitoring.
Although most patients on insulin pump therapy receive extensive education and training on numeracy-related topics, it is unknown how effective this education is or if the education is delivered at an appropriate level to ensure proper use. Currently, educational materials provided to patients with diabetes are lacking in readability, especially in relation to numeracy . For example, the education workbooks provided by the three most common insulin pump manufacturers require numeracy skills well above the average adult to understand their content . DN skills should be assessed in all patients on insulin pump therapy, and education should be delivered at an appropriate level to ensure safe and effective use [17, 27, 28]. Further research is needed on the relationships between DN and the safety and efficacy of insulin pump usage.