Income and Severe Hypoglycemia in Type 2 Diabetes.

Importance: Socioeconomic disparities are increasingly recognized as key factors in health outcomes among patients with type 2 diabetes. Understanding how income level and its changes are associated with severe hypoglycemia risk may inform targeted interventions and policy decisions.

Objective: To evaluate the association between income level, including changes in income status, and the risk of severe hypoglycemia, and to assess whether this association varies across key subgroups in middle-aged adults.

Design, setting, and participants: This retrospective cohort study included adults aged 40 to 70 years with type 2 diabetes from the Korean National Health Information Database (NHID) who underwent health examinations from 2015 to 2016. Participants aged 40 to 70 years with type 2 diabetes and valid income information were recruited between 2006 and 2010 from the UK Biobank (UKBB) and were included for sensitivity analysis. Data were analyzed from January 2023 to September 2024.

Exposures: Participants were categorized into annual income quartiles (NHID) or self-reported income brackets (UKBB). In the NHID, medical aid beneficiaries (ie, those receiving government medical aid due to income below 40% of the median income and limited assets) were identified, and income changes over a 5-year period were assessed.

Main outcomes and measures: Severe hypoglycemia requiring medical intervention.

Results: Among 1 838 362 adults with type 2 diabetes from the NHID (mean [SD] age, 57.1 [8.1] years; 1 157 263 [63.0%] male) and 17 287 participants from the UKBB (mean [SD] age, 56.9 [6.8] years; 11 522 [66.7%] male), lower income was associated with a higher risk of severe hypoglycemia (NHID: hazard ratio [HR], 2.50; 95% CI, 2.33-2.57; UKBB: HR, 5.38; 95% CI, 1.72-16.85). In the NHID, individuals whose income increased from the lowest quartile or medical aid status to the fourth quartile over 5 years had a significantly lower risk (HR, 0.74; 95% CI, 0.67-0.81; P for trend <.001), whereas receiving medical aid for at least 1 year was associated with a significantly higher risk (HR, 1.71; 95% CI, 1.54-1.89). The association between income and severe hypoglycemia was consistently greater in men, individuals not using insulin, those without chronic kidney disease, and those with a shorter duration of diabetes.

Conclusions and relevance: In this cohort study of adults with type 2 diabetes, low income was found to be a significant factor associated with risk for severe hypoglycemia. Addressing socioeconomic disparities and implementing targeted interventions may help reduce the incidence and severity of hypoglycemia.