Conclusions
In this cross-sectional study comparing insulin pump use in Canadian provinces with and without government-funded insulin pump programs for adults with type 1 diabetes, insulin pump use was more common in provinces with pump funding programs compared with provinces without. After adjustment for potential confounders, individuals living in provinces with government-funded insulin pump programs were approximately 50% more likely to use insulin pumps compared with provinces without funding programs. This is important because insulin pump therapy may improve glycemic control, reduces the rate of severe hypoglycemia, and is associated with greater quality of life.2–6 While we hypothesized that government-funded insulin pump programs may remove financial barriers to insulin pump use, we found a substantial residual association of higher income with insulin pump use even in provinces with pump funding programs. Therefore, these findings suggest that while government funding may improve access to insulin pumps, they may inadvertently favor those of higher socioeconomic status.
The total proportion of individuals using insulin pumps in this study was 46%, which may be an overestimate due to our definition of pump use based on insulin prescriptions. Furthermore, our algorithm restricted identification of type 1 diabetes to individuals between the ages of 18 and 55 and, since insulin pump use is more common in younger ages, this might have also inflated the proportion of pump users in both provinces with and without insulin pump funding programs.24 There is limited knowledge of the true proportion of insulin pump use among individuals with type 1 diabetes in Canada currently, and our study provides the only estimates to date among adults in population-based samples for many provinces. Insulin pump use in the current study is similar to 44% reported in the Canadian Study of Longevity in Diabetes, although that study represented a selected cohort of older individuals with type 1 diabetes and was susceptible to volunteer bias.25 In a population-based study using Ontario primary care EMR data, the proportion of adults with type 1 diabetes using insulin pumps was 32%.14 Among the pediatric population (<18 years old) in Ontario, the proportion using insulin pumps in 2012 was reported as 38%, though this has likely increased since.26 Internationally, the reported proportions of individuals with type 1 diabetes using insulin pumps in countries with government-funded insulin pump programs are also lower than observed in the current study (eg, 11% for all ages in New Zealand,9 20% for all ages in Sweden,27 21% for adults in Denmark,11 and 37% for adults in Germany and Austria24). Australia, a country with no funding program for insulin pumps, has reported insulin pump use among only 10% of individuals of all ages with type 1 diabetes.28 Even though we may have overestimated the number of individuals using insulin pumps, this would have been a non-differential bias, affecting individuals in provinces with and without pump funding programs similarly. Thus, the 10% difference in pump use between provinces with and without pump funding programs is valid, even if the absolute numbers of pump users within each type of province may be overestimated.
Socioeconomic disparities between pump users and non-users have been well described. The cost of insulin pumps and supplies are the most commonly reported barrier by patients against initiation of insulin pump therapy,29 and insulin pump use is consistently less common among lower income individuals compared with higher income individuals, even in countries with government-funded insulin pump programs.12 13 This is consistent with the pediatric population in Ontario, as patients from lower income backgrounds are less likely to use insulin pumps and more likely to discontinue pump therapy.30 In Brazil, where insulin pumps are paid out of pocket, pump users have higher levels of education than non-users.12 This may be explained by the tendency for practitioners to prescribe insulin pump therapy to individuals who they believe are ‘more educationally able’ to operate an insulin pump.31 In addition, education and income are correlated.32 Ethnic minorities are also consistently less likely to use insulin pumps.9 12 13 For example, in the USA, insulin pump use is significantly lower among individuals from Black and Hispanic backgrounds,13 while in New Zealand, this disparity is noted for individuals from Maori, Asian, and Pacific backgrounds.9 Although numerous explanations for this ethnic disparity may exist, having a non-English primary language may be an additional barrier to insulin pump use.33 Finally, area of residence may also influence insulin pump accessibility, with wide geographic variation in the rate of insulin pump use evident within many countries.9 11 34 Individuals living in rural areas are less likely to be prescribed insulin pump therapy compared with urban areas,35 which may be explained by differences in access to medical centers with greater resources for managing patients using insulin pumps.36
Our study showed higher rates of insulin pump use in provinces with pump funding programs, which may be due to minimizing financial barriers. However, we observed persistent disparities in income quintile even in provinces with pump funding programs, and the disparities by income quintile were not greater in provinces without pump funding programs as would have been expected. Differences in insulin pump use within each income quintile by pump funding program status were greatest in the lowest income quintile (insulin pump use was 7% higher in provinces with pump funding programs) and the highest income quintile (pump use was 5% higher in provinces with pump funding programs), whereas the rates of insulin pump use were more similar in the middle-income quintiles. Although it is unclear why this disparity would be higher in the highest income quintile, these results must be interpreted with caution since sample sizes by income quintile were small for provinces without pump funding programs, and differences within income quintiles were not statistically significant. Additionally, this may have been due to insensitive measures for socioeconomic variables since education, ethnicity, occupation and primary language were not available in the database, and income quintile was based on neighborhood averages. Furthermore, removing financial barriers to insulin pumps may not be sufficient for overcoming barriers to insulin pump use. Residual barriers might include insufficient resources for supporting insulin pump therapy, such as availability of healthcare providers and appropriate education and training.37 For example, despite having universal access to insulin pump therapy since 2012, New Zealand continues to report significant disparities in insulin pump use between different geographical regions.9 Enrollment in government-funded insulin pump programs may also require fulfilling certain criteria and managing and completing paperwork regularly, which could be an additional barrier disproportionately affecting individuals with a non-English primary language or lower education level. Thus, while government funding for insulin pumps may reduce disparities in access, more comprehensive approaches are likely needed to address additional and related barriers to insulin pump use, such as language, education, and access to expert health teams. Whether government funding for insulin pumps affects all individuals similarly or whether this differs based on characteristics such as age, sex, ethnicity, glycemic control or other factors remains unknown.
Our study has a number of strengths. First, this is one of the only estimates to our knowledge of the proportion of individuals with type 1 diabetes using insulin pumps in Canada. Second, our study is unique in that differing provincial policies for insulin pump funding permitted a ‘natural experiment’ within the same country. To our knowledge, there are no previous studies that have examined the effects of insulin pump funding programs on accessibility and use of insulin pumps. Third, our sample is less susceptible to selection bias than those obtained from diabetes specialist clinics which would be more likely to overestimate insulin pump use. Finally, we demonstrated the utility of the new DAC National Diabetes Repository for conducting health services research across multiple provinces in Canada. However, our study also has some limitations. First, there may have been misclassification of type 1 diabetes and insulin pump use. As noted previously, we expect this would have affected provinces with pump funding programs and provinces without pump funding programs similarly, resulting in a non-differential bias. Individuals who recently switched from MDI to insulin pump therapy or those using basal insulin in combination with an insulin pump may have been misclassified as not using insulin pump therapy, though we expect this would be uncommon. It is difficult to validate our estimated proportion of people with diabetes having type 1 diabetes and proportion of people with type 1 diabetes using insulin pumps given the limited reporting of such data in Canada. Second, the DAC National Diabetes Repository did not contain information pertaining to ethnicity, education, primary language, self-reported income, duration of diabetes, age at initiation of insulin pump therapy, or diabetes complications. It also did not include information regarding use of other diabetes technologies such as continuous glucose-monitoring devices. Third, our study population may be affected by bias due to a number of reasons including the algorithm being 73% sensitive and thus misclassifying some individuals with type 1 as having type 2 diabetes, the possibility that some individuals with type 1 diabetes do not regularly see a primary care provider (since specialists typically manage type 1 diabetes in Canada), and being limited to including individuals between the ages of 18 and 55. The sample size was particularly small for provinces without insulin pump funding programs which limits comparison between groups. Finally, as for all observational studies, we cannot conclude there is a causal relationship between pump funding programs and the observed association with insulin pump use.
Using a natural experiment to examine the effects of differing policies for insulin pump reimbursement on rates of insulin pump use, we demonstrated that insulin pump use is more common in regions with reimbursement programs. However, current government funding for insulin pumps does not appear to be sufficient to address disparities—such as higher income—between pump users and non-users. Given the benefits of insulin pump therapy and the emerging promise of closed-loop systems (which require both insulin pumps and continuous glucose-monitoring devices), comprehensive strategies for improving equitable use of insulin pumps are urgently required.