Pecori Giraldi F, Leoni O. Environment and diabetes: Is there an association between the COVID-19 pandemic and phenotypic variation in diabetes? World J Diabetes 2026; 17(4): 115328 [DOI: 10.4239/wjd.v17.i4.115328]
Corresponding Author of This Article
Francesca Pecori Giraldi, Associate Professor, Department of Clinical Sciences & Community Health, University of Milan, Via Commenda 19, Milan 20122, Lombardy, Italy. francesca.pecorigiraldi@unimi.it
Research Domain of This Article
Endocrinology & Metabolism
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Retrospective Cohort Study
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This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/
Apr 15, 2026 (publication date) through Apr 14, 2026
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Publication Name
World Journal of Diabetes
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1948-9358
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Baishideng Publishing Group Inc, 7041 Koll Center Parkway, Suite 160, Pleasanton, CA 94566, USA
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Pecori Giraldi F, Leoni O. Environment and diabetes: Is there an association between the COVID-19 pandemic and phenotypic variation in diabetes? World J Diabetes 2026; 17(4): 115328 [DOI: 10.4239/wjd.v17.i4.115328]
World J Diabetes. Apr 15, 2026; 17(4): 115328 Published online Apr 15, 2026. doi: 10.4239/wjd.v17.i4.115328
Environment and diabetes: Is there an association between the COVID-19 pandemic and phenotypic variation in diabetes?
Francesca Pecori Giraldi, Olivia Leoni
Francesca Pecori Giraldi, Department of Clinical Sciences & Community Health, Deparment of Excellence 2023-2027, University of Milan, Milan 20122, Lombardy, Italy
Olivia Leoni, Data Monitoring and Control Unit, Welfare Governance, Regione Lombardia, Milan 20122, Lombardy, Italy
Author contributions: Pecori Giraldi F performed study design, data collection and analysis, and drafted manuscript; Leoni O curated methodology and project administration; Pecori Giraldi F and Leoni O revised and approved the final manuscript.
Institutional review board statement: The study was approved by the Ethical Committee of the University of Milan.
Informed consent statement: Not required (data anonymized by data warehouse software).
Conflict-of-interest statement: Pecori Giraldi F has no conflict of interest to disclose; Leoni O is an employee of Regione Lombardia, the state-funded Health Care Provider.
STROBE statement: The authors have read the STROBE Statement—checklist of items, and the manuscript was prepared and revised according to the STROBE Statement—checklist of items.
Data sharing statement: Data that support the findings of this study were created under license for the current study and are therefore not publicly available. As per the undersigned agreement, data ownership rests with the Regione Lombardia.
Corresponding author: Francesca Pecori Giraldi, Associate Professor, Department of Clinical Sciences & Community Health, University of Milan, Via Commenda 19, Milan 20122, Lombardy, Italy. francesca.pecorigiraldi@unimi.it
Received: October 14, 2025 Revised: December 8, 2025 Accepted: February 4, 2026 Published online: April 15, 2026 Processing time: 182 Days and 15.5 Hours
Abstract
BACKGROUND
The development of diabetes is linked to the environment, and major lifestyle changes are known to affect the incidence of diabetes. The recent coronavirus disease 2019 (COVID-19) pandemic changed many aspects of daily life and represents a major environmental effect.
AIM
To investigate whether the COVID-19 pandemic affected the presentation of diabetes in adults.
METHODS
A retrospective fixed cohort study was performed on the Lombard population, one of the hardest hit by the pandemic in Italy. Records from 57870 adults (40-65 years) with diabetes were extracted from the Lombard healthcare database for pandemic (2020-2021) and control (2018-2019) cohorts. Demographic data and data pertaining to concomitant cardiovascular disorders were analyzed. Cohen’s d and rate ratio with 95% confidence interval (CI) were calculated.
RESULTS
During the pandemic, the incidence of newly diagnosed diabetes was greater among men aged 40-46 years old (rate ratio = 1.07, 95%CI: 1.01-1.14) and less among older men (59-65 years old; rate ratio = 0.94; 95%CI: 0.90-0.96) compared with the control cohort. The rate of incident diabetic men with hypertension, hyperlipidemia, cardiovascular events, or prescriptions for cardiovascular-acting medications during the pandemic was lower compared with individuals in the control cohort (rate ratio for cardiovascular risk factors = 0.893; 95%CI: 0.87-0.92). A similar pattern was observed among women diagnosed with diabetes during the pandemic (rate ratio for cardiovascular risk factors = 0.899; 95%CI: 0.87-0.93).
CONCLUSION
The COVID-19 pandemic was associated with greater incident diabetes in younger individuals with fewer cardiovascular comorbidities and suggest that a potent environmental change such as the pandemic can affect the diabetes phenotype in adults.
Core Tip: The development of diabetes is linked to the environment, and major lifestyle changes are known to affect its incidence . The coronavirus disease 2019 pandemic represented a major environmental disruption; however, its impact on diabetes phenotype has not yet been fully evaluated. In this study, we compared adults diagnosed with diabetes during the pandemic in Lombardy, one of the Italian regions most heavily affected, with individuals diagnosed before 2020. We observed a higher incidence of diabetes among younger individuals without cardiovascular comorbidities in 2020-2021, suggesting that a potent environmental factor, such as the pandemic, may influence the phenotype of incident diabetes.
