Revision

Add explanation on SVI, its benefits and shortcomings/ limitations

Background

Diabetes mellitus (DM) is a public health crisis affecting over 500 million people worldwide1. In the United States (US) alone, more than 38 million adults 18 years or older are currently living with the disease, with disproportionately higher morbidity and mortality reported among underserved populations2. Social determinants of health (SDOH), including a lack of health insurance, inability to afford medications, poor socioeconomic status (SES), and inequities in living conditions, have been identified as key contributors to the relatively higher disease burden among underserved populations3. Higher disease burden has been associated with higher risk for micro- and macrovascular complications such as diabetic retinopathy and chronic kidney disease, poorer long-term outcomes, increased healthcare utilization, and premature death3-4.

The Centers for Disease Control and Prevention (CDC) defines social vulnerability as the potential adverse effects of demographic and socioeconomic stressors, such as poverty and lack of health insurance, on communities5. Social vulnerability index (SVI), a CDC place-based index and database, maps communities within the US to quantify them based on the severity of social vulnerability. Communities are categorized into one of four quartiles, with the former representing the least vulnerable and the latter, the most vulnerable. Essentially, the higher the quartile, the greater the SDOH burden experienced within a community5.This is made evident in a study by Bashar et al. (2023), which found that persons with DM living in higher SVI areas are 2 to 4 times more likely to die from cardiovascular complications compared to those in less vulnerable areas.4 Further, a cross-sectional study by Winberg et al. (2025) also found that persons with DM residing in moderate vulnerability communities are less likely to perform good self-management behaviors, such as glucose self-monitoring, a factor that can contribute to poor glycemic control and potentially lead to negative clinical outcomes6.

Previous studies have established that free clinics providing care and education to uninsured patients with DM can improve clinical outcomes, primarily a reduction in hemoglobin A1c (HbA1c) levels7-8. In a single-center retrospective study, Bias et al. (2023) also found that individuals with DM enrolled in a prescription assistance program (PAP) by a pharmacist experienced greater reduction in HbA1c and weight compared to the control group9. A similar study by Strum et al. (2005) also found that a clinic-based medication assistance program increased access to antihyperglycemic medications and improved clinical outcomes among patients with DM10.

In the US, the Dispensary of Hope (DOH) program distributes medications donated by pharmaceutical companies at no cost to uninsured patients to facilitate access; of note, healthcare facilities must pay an annual fee to access formulary medications for these patients11. A retrospective observational study (Hughes et al., 2023) which examined the impact of free DM medications dispensed through DOH-partner pharmacies on HbA1c reported a significant improvement in glycemic levels. However, this was a single-site study with a small sample12. Further, clinical parameters such as body mass index (BMI), blood pressure (BP), and low-density lipoprotein (LDL), pertinent to effective DM management, were not examined. Notably, none of the aforementioned studies investigated the potential impact of SVI on glycemic control. This study provides a larger sample size, and the evaluation of a free medication program and SVI on clinical outcomes.

References

Bashar, H., Kobo, O., Khunti, K., Banerjee, A., Bullock-Palmer, R. P., Curzen, N., & Mamas, M. A. (2023). Impact of Social Vulnerability on DiabetesRelated Cardiovascular Mortality in the United States. Journal of the American Heart Association.

Centers for Disease Control and Prevention. (2024a, May 15). National diabetes statistics report. Centers for Disease Control and Prevention.

Centers for Disease Control and Prevention. (2024b, October 22). Social Vulnerability Index. Place and Health – Geospatial Research, Analysis, and Services Program (GRASP).

Dispensary of Hope. (n.d.). Home. .

Hill-Briggs, F. (2020). Social determinants of health and diabetes: A scientific review. Diabetes Care, 44(1), 258279.

Winberg, D., Marchi, N., Tang, T., & Shi, L. (2025). Association Between Diabetes Management Behaviors and State-Level Social Vulnerability: A Cross-sectional Study. Diabetes Therapy.