Financial burden of glycemic control: a single-center retrospective study of diabetes costs in South Korean patients

Background/Aims: The impact of glycemic control on healthcare costs is a critical research area. In this study, we aimed to evaluate the relationship between hemoglobin A1c (HbA1c) levels and healthcare costs, including out-of-pocket (OOP) expenses and insurance expenditures (IEs), over 5 years (2019–2023).Methods: This retrospective cohort study was conducted using data from Uijeongbu St. Mary’s Hospital of patients who underwent HbA1c testing between January 1, 2019 and December 31, 2023. Patients were categorized as normal glycemic group (NG, HbA1c < 6.5%), moderately hyperglycemic group (MG, 6.5–8%), and highly hyperglycemic group (HG, ≥ 8%). Univariate linear regression was used for evaluating associations between HbA1c levels and healthcare costs.Results: Of 86,417 patients, 61,961, 15,065, and 9,391 were NG, MG, and HG, respectively. The HG group had the highest 75th percentile cost at 9,339 USD, compared with 7,673 and 8,741 USD in the NG and MG groups, respectively. Each 1% increase in HbA1c level was associated with an additional 236.11 USD in total costs, including 55.58 and 180.53 USD in OOP expenses and IEs, respectively. Patients with worsened glycemic control had the highest total healthcare costs (up to 12,742 USD), whereas those with improved glycemic control showed consistently lower total and inpatient costs. Higher costs were also observed among patients with diabetes, chronic kidney disease, serious disease exemption status (particularly those with poorly controlled diabetes), and those receiving medical aid.Conclusions: Elevated HbA1c levels were associated with increased healthcare costs. Effective glycemic control might help reduce financial burdens.