Introduction
Diabetes is a major public health problem with a significant economic burden as evidenced by the fact that the average healthcare expenditure of a patient with diabetes is 2.3 times higher than that of a patient without diabetes ( Yang et al., 2018 ). Adults with poorly managed diabetes may suffer from short-term complications such as hypoglycemia, hyperglycemia, diabetic ketoacidosis, and long-term complications such as stroke, heart failure, retinopathy, neuropathy, nephropathy, and diabetes-related foot problems such as gangrene, ulcer, Charcot’s foot, and amputation ( Mayo Clinic, 2020 ; Khan et al., 2022 ). There is evidence that the risk of Emergency Department (ED) visits is higher among persons with diabetes (68 visits/100 persons) than the national average (42.7 visits/100 persons) ( Centers for Disease Control and Prevention, 2021a , 2021b ). In 2015, about 24% of all ED visits for patients aged 45 or older involved people with diabetes ( Washington, Andrews & Mutter, 2013 ; Hall, Rui & Schwartzman, 2018 ). Out of 130 million ED visits in 2018 in the US, approximately 17 million visits were due to diabetes and diabetes-related complications.

Emergency departments play a vital role at the interface between the population and the healthcare system. Investigating patterns in the use of ED visits can help identify patterns of health resource utilization, identify disease trends and emerging threats, as well as assess the magnitude and management of disease problems ( Kellermann et al., 2013 ). Previous studies reported that diabetes-related ED visits varied by age, race, ethnicity, income levels, and types of diabetes-related complications ( Washington, Andrews & Mutter, 2013 ; Ginde, Espinola & Camargo, 2008 ; Menchine et al., 2012 ; Benoit et al., 2020 ). Not surprisingly, the southern states of the US, including Florida, have considerably higher diabetes-related ED visits than the rest of the country ( Washington, Andrews & Mutter, 2013 ). A study identified this region as the diabetes belt, an area where diabetes prevalence was significantly higher than the rest of the US ( Barker et al., 2011 ). However, diabetes management programs are not equitably distributed in this area and significant disparities exist in the use of available diabetes management programs ( Khan et al., 2021 ). Lack of access to appropriate and timely diabetes care for some individuals with diabetes results in poor management of the condition leading to otherwise avoidable diabetes-related ED visits resulting in geographic disparities in ED visits ( Ricci-Cabello et al., 2010 ; Barker et al., 2011 ; Shrestha, 2012 ; Walker et al., 2014 , 2015 ; Lord, Roberson & Odoi, 2020 ). Identifying these disparities is important in guiding health planning for these patients. Although a study investigated geographic disparities in diabetes-related ED visits in the US at the regional level ( Menchine et al., 2012 ), no such studies have been done at lower geographic scales and yet this information is important for guiding resource allocation to address the problem at the local level.

Diabetes is considered an ambulatory care sensitive condition (ACSC), a condition in which appropriate ambulatory/outpatient care can prevent complications and the need for ED visits and hospitalizations ( Agency for Healthcare Research and Quality, 2001 ). Therefore, disparities in diabetes-related ED visit may indicate differential outpatient care access, continuity, and quality ( Johnson et al., 2012 ). Previous studies identified disparities in ED utilization among traditionally underserved groups such as Black, Hispanic, uninsured, and low-income patients ( Sun, Burstin & Brennan, 2003 ; Hong, Baumann & Boudreaux, 2007 ). Since non-Hispanic Black and Hispanic populations represent almost half of the Florida population and there is evidence of a 54% increase in diabetes-related ED visits in Florida between 2011 and 2016, investigating temporal changes and geographic disparities in diabetes-related ED visits is necessary for a better understanding of diabetes burden in Florida ( Florida Diabetes Advisory Council, 2019 ; Florida Department of Health, 2022 ). Identifying areas with high diabetes-related ED visit rates in Florida could help identify areas with inadequate access to ambulatory care and poor quality of diabetes management ( Dowd et al., 2014 ). This knowledge is important for planning programs targeted at improving access to primary diabetes care, reducing the burden of the condition and its complications, and improving population health. In addition, socioeconomic and demographic predictors of disparities in diabetes-related ED visits, if identified, would help guide resource allocation geared towards reducing disparities in availability of diabetes care as well as diabetes burden in Florida. Therefore, the objectives of this study were to: a) investigate geographic disparities and temporal changes in non-gestational diabetes-related ED visit rates in Florida between 2016 and 2019; b) identify predictors of geographic disparities in non-gestational diabetes-related ED visit rates in Florida.