The difference in type 2 diabetes care between the National Health Insurance beneficiaries and public assistance recipients in Japan: A retrospective cohort study based on claims data in a municipality

Aims/Introduction We examined the differences in diabetes care between public assistance recipients (PARs), exempt from medical costs and guaranteed a minimum income, and the National Health Insurance (NHI) beneficiaries, covering non‐employed and self‐employed individuals with some cost sharing in Japan. Materials and Methods This observational study used claims data from a Japanese municipality (April 2017–March 2022) to identify individuals aged 20–68 with type 2 diabetes on antidiabetic medications. We analyzed care processes annually and cross‐sectionally, focusing on tests, medications, and medical costs, and followed health outcomes (hypoglycemia and hospitalization) monthly and longitudinally. Multivariable Poisson regression models estimate the risk ratios for binary care processes, and a gamma regression model analyzes medical costs as continuous variables. Health outcome incidence rate ratios were assessed using multivariable Poisson regression, with the observation period as an offset. Results We included cross‐sectional data from 11,385, 11,566, and 9,943 people (2018–2020) and longitudinal data from 18,655 individuals. In the analysis considering the whole periods, PARs were more likely to receive annual eye examinations (adjusted risk ratio 1.15, 95% confidence interval [CI] 1.08–1.22), use sodium‐glucose cotransporter‐2 inhibitors (1.22, 1.13–1.31), and use glucagon‐like peptide‐1 receptor agonists (1.63, 1.41–1.90). The total (1.16, 1.09–1.23) and outpatient medical costs (1.31, 1.24–1.38) were higher, whereas the inpatient costs (0.85, 0.77–0.94) were lower for PARs. Hypoglycemia incidence was also higher (adjusted incidence rate ratio 2.21, 95% CI 1.38–3.54). Conclusions Public assistance might improve the diabetes care process, but not fully health outcomes. These findings suggest additional supports for PARs and further research for NHI beneficiaries in poverty.