Residents of areas with a higher Climate Vulnerability Index (CVI) were significantly more likely to develop type 2 diabetes (T2D) independent of other risk factors, in a study based on data from more than 1 million individuals.

“Climate change and social vulnerability are increasingly recognized as contributors to chronic disease, yet no prior work had examined whether a multidimensional climate vulnerability measure is linked to new-onset [T2D],” said lead study author Jad Ardakani, MD, a postdoctoral clinical research fellow at the Houston Methodist DeBakey Heart & Vascular Center in Houston.

“Rising heat, infrastructure stresses, and socioeconomic disparities across regions like Houston made it timely to evaluate whether place-based vulnerability adds meaningful risk information for diabetes beyond traditional factors,” he told Medscape Medical News.

The US CVI was designed to assess the interactions between climate risks and health at the neighborhood level in order to inform research, funding, and policy decisions. It uses 184 indicators to evaluate the conditions that shape a community, from housing quality and supermarket access to nearby toxic waste sites. These findings are combined into seven vulnerability and risk categories, including health, environment, infrastructure, social and economic, and others, to determine the overall CVI for each community.

CVI and T2D Risk

In a study published in JAMA Network Open, the researchers reviewed data from 1,003,526 adults aged 18 years or older who had at least one outpatient encounter and one subsequent healthcare encounter at a single center in Texas between June 2016 and August 2023. The mean age of the participants was 51 years, and 60% were women; 57% were White, 16% were Hispanic, 13% were Black, 7% were Asian, and 4% were of other ethnicity or ethnicity unknown. The overall incidence of T2D was 1.88 cases per 100 person-years over a follow-up period up to 7 years.

Patients were divided into CVI quartiles based on residential addresses recorded in their electronic health records.

Overall, the risk for T2D was significantly associated with residence in the highest CVI quartile vs the lowest CVI quartile, independent of demographic socioeconomic and clinical factors (hazard ratio [HR], 1.23).

Diabetes incidence was approximately twice as high among participants residing in the highest vs the lowest CVI quartile (2.66 vs 1.48 cases per 100 person-years). In addition, the risk for T2D over the 7-year follow-up period was significantly higher among the highest CVI quartile residents than among the lowest CVI quartile residents (14.1% vs 8.6%).

The magnitude of the association varied by clinical and demographic subgroups, with higher HRs for individuals younger than 50 years (HR, 1.52; 95% CI, 1.47-1.57), women, and individuals who were Hispanic or White or of other ethnicities.

“The overall association was expected, but the strength of the relationship in younger adults and those with normal BMI was notable,” said Ardakani. “This pattern suggests that environmental and structural vulnerabilities may accelerate metabolic risk even before traditional risk factors appear.”

“The large contribution from infrastructure and socioeconomic domains was also striking, reinforcing how strongly structural inequities influence diabetes development,” he said.

More research is needed to identify the mechanisms behind the association between CVI and T2D, but the results suggest value in using CVI to assess risk at the local level and inform tailored public health outreach and interventions, Ardakani and colleagues concluded.

Action Items for Practice

One thing to do would be to incorporate neighborhood context into risk assessment, especially for patients in highly vulnerable census tracts, Ardakani told Medscape Medical News.

Other actions include increased screening for prediabetes and metabolic risk in individuals from high-CVI areas, even when BMI is normal, and prioritizing referrals to diabetes prevention programs, nutrition services, and physical activity resources for patients living in vulnerable communities, he said. In addition, geocoded indices such as CVI could be used to guide population health outreach and tailor preventive strategies, he noted.

Ardakani acknowledged that the study was limited by several factors, including the single-system design, reliance on administrative data, limited individual-level socioeconomic and lifestyle information, and potential residual confounding.

“Additional research should validate these findings in other regions, explore causal pathways including specific environmental exposures, and test interventions that reduce diabetes risk in climate-vulnerable neighborhoods,” he said.

Consider Climate’s Chronic Effects

“Climate change is lived as a chronic condition, not just experienced as episodic crises such as stifling heat waves or devastating flooding,” Charles E. Leonard, PharmD, MSCE, MPH, associate professor at the Perelman School of Medicine at the University of Pennsylvania in Philadelphia, told Medscape Medical News.

The current study’s overall finding, while important, was not especially surprising, although risk seemed to be driven by structural and social vulnerabilities, with climate-specific factors adding to risk rather than dominating it, Leonard noted. “Such a pattern is broadly consistent with how chronic disease develops and clusters in communities affected by long-term disinvestment,” he said.

“A seminal take-home message from the current study is the importance of context,” Leonard said. “Metabolic risk surely does not arise in isolation, and community conditions matter,” he emphasized.

Although the impact of community conditions does not change existing diabetes treatment paradigms, it may support earlier screening or closer follow-up for patients living in vulnerable environments, even when traditional risk markers such as dyslipidemia look relatively reassuring, he added.

Looking ahead, “more understanding is needed of how structural conditions, social environment, and climate-related stressors such as exposure to extreme ambient temperatures interact over time to affect diabetes risk,” said Leonard.

“Work that links these exposures longitudinally and considers how they intersect with prevention measures and access to care is essential before study findings are translated more directly into practice,” he said.

The study was funded by the Jerold B. Katz Foundation and by an award from the Cornell Atkinson Center for Sustainability. Ardakani disclosed having no financial conflicts of interest. Leonard disclosed consulting for Shine Lawyers (Australia) and Moderna and previously consulting for Novo Nordisk on diabetes topics unrelated to climate change.