Unseasonal extreme cold weather, ultrafine particles, and diabetes hospitalizations: an unexpected time window for intervention

Abstract

Background

Although the associations between ambient heat and diabetes have been assessed, the odds of ambient extreme cold exposure (ECE) or ultrafine particles (UFP) on diabetes admissions are understudied.

Objectives

We assessed the impacts of ECE on diabetes hospitalization and evaluated the modifications of demographics, comorbidities, and UFP on ECEdiabetes associations.

Methods

A time-stratified case-crossover study was conducted by using mandatory New York State (NYS) admission data (principal diagnosis, 2013–2020) and temperature and simulated UPF data from NYS Mesonet and a global chemistry transport model, respectively. We defined ECE as <5th percentile of daily mean temperature and UFP-high as >50th percentile of the daily mean UFP. After adjusting for air pollutants, humidity, and holidays, we conducted conditional logistic regressions to investigate ECE-diabetes associations, additive and multiplicative interactions between UFP, demographics/comorbidities, and ECE.

Results

Diabetes admissions associated with ECE were significantly elevated in winter months (ranges of odds ratios (ORs): 1.099–1.104, P < 0.05 in January and February) but the associations increased more consistently across multiple lag days in March (ranges of ORs: 1.068–1.129, P < 0.05). ECE-diabetes associations were significant among patients with peripheral circulatory complications and hyperglycemia compared to those without these complications. UFP-diabetes associations were significant in November (OR: 1.052, 95 % confidence interval (CI): 1.012–1.093) and December (OR: 1.045, 95 % CI: 1.003–1.088). Additionally, ECE-UFP interactions on diabetes were significant at both additive (95 % CI >0 for the attributable proportion to interactions and relative excess risk index) and multiplicative (P < 0.05 for product terms) scales. Furthermore, females, older adults, urban residents, and patients with multiple comorbidities were more vulnerable to ECE than other groups.

Conclusions

ECE-diabetes associations were significant in winter months, but the increased associations occurred more persistently in March. While synergistic and additive interactions between ECE and UFP on diabetes were found, ECE-diabetes ssociations were also modified by demographics and comorbidities.