Regional disparities in type 2 diabetes prevalence and associated risk factors in the United States

Abstract

Diabetes mellitus, a chronic condition characterized by elevated blood glucose levels resulting from insufficient insulin production or utilization, imposes substantial health and economic burdens in the United States. According to the Centers for Disease Control and Prevention, over 37 million people in the United States, or approximately one in 10 people, have diabetes, and approximately 96 million US adults, or one in three, have prediabetes.1, 2 The prevalence of diabetes has been steadily increasing over the past few decades, and it is projected to continue to rise in the coming years.2 A multitude of factors contribute to an increased risk of developing the condition, including obesity, age, sedentary lifestyles, and belonging to certain racial minorities, such as Hispanic or Latino and non-Hispanic Black populations.1 Comprehending the trends, disparities, and risk factors associated with diabetes prevalence is crucial for developing effective prevention and management strategies.2, 3 While previous studies have explored trends over past years, the association between risk factors and diabetes prevalence has not been comprehensively documented. This study aims to bridge this knowledge gap by examining recent national trends and disparities in self-reported diabetes prevalence among US adults. Data were obtained from the Behavioral Risk Factor Surveillance System (BRFSS), an ongoing health survey involving more than 400 000 adult interviews each year.4 A sample of 5 312 827 observations from 2012 to 2022 were included in this observational study. This research followed the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) guidelines and was not subject to review or informed consent under the Common Rule since it utilized secondary, de-identified data. Diabetes was defined as self-reported previous diagnosis through standardized questionnaires, offering consistency but risking potential underreporting compared to clinical measures. Sociodemographic factors comprising age, sex, race, education, income, physical activity, and body mass index were used to establish risk indicators for diabetes development. Complex sampling procedures applied appropriate weighting to sampling probabilities, ensuring representativeness and generalizability of population estimates. Age standardized diabetes prevalence was calculated overall and across various sociodemographic characteristics. Age was standardized based on the 2010 US census (three age groups 18–44 years, 45–64 years, and 65 years and above). Subsequently, logistic regression was performed to assess the association between risk factors and diabetes. Adjusted odds ratios (aORs) with 95% confidence intervals (CIs) are reported. Appendix Table A1 details the proportions for different subgroups in the study sample for each year. The overall prevalence of diabetes increased significantly by 18.6% (p < 0.001) during the study period (Table 1). The increase was observed across all sociodemographic groups, but some were affected more than others (Appendix Figure A1). Notably, the prevalence was highest among non-Hispanic Black people (15.8%), underscoring existing racial disparities. Individuals aged 65 years and over faced the highest prevalence of 23.86%, implicating an aging population as a contributory factor. The data revealed males had a slightly higher prevalence than females (12.56% vs 11.56%). Physically active individuals had a lower prevalence than inactive individuals (9.85% vs 18.98%). Individuals with lower incomes had a 56% higher prevalence than those with higher incomes. Additional analyses highlighted the importance of considering obesity as a major risk factor for diabetes, as obese individuals faced the highest prevalence of 19.23%, compared with normal-weight individuals. The South/Midwest experienced outsized increases from 9.2% to 12.8%, with states such as Arkansas, Kentucky and Nebraska reporting the highest increases (p < 0.01), warranting examination of regional determinants influencing health outcomes. Regional and population-specific insights from stratified modelling hold value for guiding targeted prevention activities (Figure 1). Table 1 shows the associations between risk factors and the prevalence of diabetes, presented as aORs and corresponding 95% CIs. Compared to females, males were more likely to be diagnosed with diabetes. Our analysis indicates that males were 1.15 (95% CI 1.13, 1.16) times more likely to be diagnosed with diabetes. We observed differences in diabetes risk among various racial and ethnic groups. Compared to non-Hispanic White individuals, Hispanic individuals had an aOR of 1.60 (95% CI 1.57, 1.64), non-Hispanic Asians had an aOR of 1.67 (95% CI 1.59, 1.76), and non-Hispanic Black individuals had an aOR of 2.10 (95% CI 1.98, 2.22). These numbers indicate an increased risk of developing diabetes compared to non-Hispanic Whites for each respective group. Adults aged 45–64 years were 5.16 times more likely to be diagnosed with diabetes (95% CI 5.05, 5.29) compared to those aged 18–24 years. Adults aged 65 years and above were 10.23 times more likely to be diagnosed with diabetes (95% CI 9.99, 10.47) compared to those aged 18–24 years. Overweight individuals had 1.57 (95% CI 1.54, 1.60) times higher odds of being diagnosed with diabetes compared to normal-weight individuals. Additionally, obese individuals were 3.64 (95% CI 3.57, 3.71) times more likely to be diagnosed with diabetes compared to normal-weight individuals. However, regular exercise can reduce the risk of diabetes diagnosis by approximately 32% (aOR 0.68 [95% CI 0.67, 0.69]). Our analysis indicates that individuals with higher income and college education were 41% (aOR 0.59 [95% CI 0.58, 0.61]) and 24% (aOR 0.76 [95% CI 0.75, 0.78]) less likely to be diagnosed with diabetes, respectively. This study showed significant increases in diabetes prevalence across the United States from 2012 to 2022, aligning with previous research demonstrating rising trends nationally over recent decades.5, 6 The 18.6% rise observed builds upon other work showing substantial growth from 1988 to 20125 and 1999 to 2016.6 Persistently high and increasing prevalence underscores the alarming diabetes epidemic facing the United States. Notably, disparities in prevalence between sociodemographic groups persisted and, in some cases, widened over this period. Higher rates among racial/ethnic minorities, males, older adults, and socioeconomically disadvantaged populations corroborate well-established inequities.7 Groups facing obesity, physical inactivity, and lower education/income bore a disproportionate burden, reflecting social determinants of health.8 Differential trends by US state also highlighted geographic disparities, with certain regions, such as the South and Midwest, experiencing more pronounced increases. Our study's findings align with previous research showing a higher prevalence of diabetes in the South,9 likely due to socioeconomic differences, access to diabetes care, region-specific programmes, policies, and cultural factors.10 Residents of the South and Midwest are more likely to be obese and to lead sedentary lifestyles, increasing their diabetes risk. The South also has a lower percentage of physically active individuals than other regions. Additionally, our data indicate higher obesity rates in the South and Midwest compared to the Northeast and West, consistent with previous findings.11 The Southern and Midwestern regions also have larger populations of non-Hispanic Black individuals, who are at higher risk of diabetes. The association between obesity and diabetes risk is well established, and our findings further emphasize the importance of addressing the obesity epidemic as a crucial step in combating the diabetes crisis. Promoting healthy eating habits, increasing physical activity, and implementing community-based interventions to support weight management can play a significant role in reducing diabetes prevalence.8, 12 Despite the advantage of having a large, nationally representative sample, this study has limitations due to potential bias from self-reported diagnoses and the lack of clinical data. Also, limitations in the data collection process prevent us from analysing diabetes prevalence among specific Asian subgroups, such as South-East Asians and South Asians. Consequently, our study cannot provide insights into the potential differences in diabetes prevalence between these subgroups. To summarize, this research revealed a significant increase in the nationwide prevalence of diabetes, which affected various sociodemographic groups differently. Disparities not only persisted but also intensified among the most vulnerable populations. Gaining insights into these trends and their driving factors is crucial for the development of focused prevention efforts. Improving access to quality care, implementing diabetes prevention programmes focusing on high-risk groups, and addressing social determinants through multilevel interventions may help curb the diabetes epidemic in the United States. Regional differences call for exploring contextual drivers such as rurality, economic conditions, and health access shaping community health outcomes to tailor place-based solutions. The authors sincerely thank Dr. Edoardo Mannucci, Associate Editor, and two anonymous reviewers for their constructive comments that have enhanched this paper. The authors received no funding for this research. The peer review history for this article is available at https://www.webofscience.com/api/gateway/wos/peer-review/10.1111/dom.15797. The data that support the findings of this study are openly available at https://www.cdc.gov/brfss/annual_data/annual_data.htm.

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