Incident diabetes within the first two years after SARS-CoV-2 infection: a population-based retrospective cohort study of the Agency for Health Protection of Milan, Italy

BACKGROUND: Postacute sequelae of SARS-CoV-2 infection (PASC), including persistent symptoms and acute and chronic diagnoses, have become a major research focus. Diabetes mellitus, beyond its established link to COVID-19 severity, is increasingly recognized as a potential long-term outcome. This study investigated the association between SARS-CoV-2 infection and incident diabetes using population-level health administrative data (HAD) from the Agency for Health Protection of Milan, where the epicenter of the pandemic in Italy took place. METHODS: This retrospective cohort study included adult residents without a history of diabetes who underwent SARS-CoV-2 testing between 1 March and 31 December 2020. Test-positive individuals were matched 1:1 to test-negative individuals based on sex, age, and testing week. The cohort was followed through 31 December 2021. The incidence of diabetes, identified using an HAD-based case-detection algorithm, was compared between the two groups, and in stratified analyses by sex and age, using weighted Cox models adjusted for chronic comorbidities, area-level deprivation, influenza and pneumococcal vaccinations. Weights were calculated via the inverse probability weighting approach. Effect estimates are presented as hazard ratios (HRs). RESULTS: Our final cohort included 248,176 residents (124,026 test-negative, 124,150 test-positive). Over a median follow-up time of 415 days, 739 positive (0.60%) and 657 negative (0.53%) individuals were newly identified with diabetes. The incidence among positive individuals was 572.82 per 100,000 person-years (CI 531.52-614.12), and that among negative individuals was 509.50 per 100,000 person-years (CI 470.54-548.46). The overall HR was 1.13 (CI 1.02-1.25). In stratified analyses, this effect was prominent in women aged 41-60 years (HR 1.31; CI 1.02-1.68). CONCLUSIONS: This study provides population-based evidence supporting an association between SARS-CoV-2 infection and newly detected diabetes. These findings contribute to understanding the long-term health impact of COVID-19 and may inform public health strategies for PASC prevention and management.

Authors

Institutions

Publication Details

Journal
BMC Infectious Diseases
Published
2026-05-11
DOI
https://doi.org/10.1186/s12879-026-13467-4
Primary Topic
Diabetes and associated disorders
Type
article
Field-Weighted Citation Impact
0.00

Funders

Controls
|||
ALL TIME
JAN
FEB
MAR
APR
MAY
JUN
JUL
AUG
SEP
OCT
article

Incident diabetes within the first two years after SARS-CoV-2 infection: a population-based retrospective cohort study of the Agency for Health Protection of Milan, Italy

Stefano Denicolai, Anna Clara Fanetti, Simona Migliazza, Giovanni Maifredi et al.
BMC Infectious Diseases
Diabetes and associated disorders
article

Incident diabetes within the first two years after SARS-CoV-2 infection: a population-based retrospective cohort study of the Agency for Health Protection of Milan, Italy

Stefano Denicolai, Anna Clara Fanetti, Simona Migliazza, Giovanni Maifredi, Vincenzo Belcastro, Marco Villa, M Rognoni, Claudio Lucifora, Diala Kabbara, Giuseppe Emanuele La Piana, Paolo Sacchi, Valentina Zuccaro, Silvia Tillati, Federico Franzoni, Stefano Rusconi, Elena Tassistro, Rossella Murtas, Simona Dalle Carbonare, Luigi Magnani, Cristina Mazzali, Monica Lanzoni, Linda Guarda, Ivan Cometti, Daria Vigani, Maurizio Morlotti, Luca Cavalieri d’Oro, Pietro Magnoni, Giacomo Crotti, Giuseppe Lapadula, Anita Andreano, Alberto Zucchi, Giuseppe Sampietro, Andrea Salvatori, Andrea Patroni, Maria Letizia Gambino, Pietro Perotti, Adele Zanfino, Alberto Milanese, Costanza Baldrighi, Gabriele Letta, Piersimone Fontana, Elisabetta Pagani, Deborah Testa, Sara Tunesi, Antonio Giampiero Russo, the PASCNET study group, Elisabetta Merlo, Maria Grazia Valsecchi, Marica Grego, Laura Antolini, Federica Manzoni, Raffaele Bruno, Anna Bussi
article en

Abstract

BACKGROUND: Postacute sequelae of SARS-CoV-2 infection (PASC), including persistent symptoms and acute and chronic diagnoses, have become a major research focus. Diabetes mellitus, beyond its established link to COVID-19 severity, is increasingly recognized as a potential long-term outcome. This study investigated the association between SARS-CoV-2 infection and incident diabetes using population-level health administrative data (HAD) from the Agency for Health Protection of Milan, where the epicenter of the pandemic in Italy took place. METHODS: This retrospective cohort study included adult residents without a history of diabetes who underwent SARS-CoV-2 testing between 1 March and 31 December 2020. Test-positive individuals were matched 1:1 to test-negative individuals based on sex, age, and testing week. The cohort was followed through 31 December 2021. The incidence of diabetes, identified using an HAD-based case-detection algorithm, was compared between the two groups, and in stratified analyses by sex and age, using weighted Cox models adjusted for chronic comorbidities, area-level deprivation, influenza and pneumococcal vaccinations. Weights were calculated via the inverse probability weighting approach. Effect estimates are presented as hazard ratios (HRs). RESULTS: Our final cohort included 248,176 residents (124,026 test-negative, 124,150 test-positive). Over a median follow-up time of 415 days, 739 positive (0.60%) and 657 negative (0.53%) individuals were newly identified with diabetes. The incidence among positive individuals was 572.82 per 100,000 person-years (CI 531.52-614.12), and that among negative individuals was 509.50 per 100,000 person-years (CI 470.54-548.46). The overall HR was 1.13 (CI 1.02-1.25). In stratified analyses, this effect was prominent in women aged 41-60 years (HR 1.31; CI 1.02-1.68). CONCLUSIONS: This study provides population-based evidence supporting an association between SARS-CoV-2 infection and newly detected diabetes. These findings contribute to understanding the long-term health impact of COVID-19 and may inform public health strategies for PASC prevention and management.

BMC Infectious Diseases
University of Bergamo (IT), Agenzia Regionale per la Protezione Ambientale del Piemonte (IT), University of Insubria (IT), University of Pavia (IT), Ospedale Civile di Voghera (IT), Health Protection Agency (MV), Presidio Ospedaliero (IT), Azienda Ospedaliera Ospedale Maggiore (IT), Ospedale Maggiore di Lodi (IT), Policlinico San Matteo Fondazione (IT), University of the Sacred Heart (JP), Istituti di Ricovero e Cura a Carattere Scientifico (IT), Azienda Ospedaliera Ospedale Civile di Legnano (IT), University of Milano-Bicocca (IT), University of Brescia (IT)
Fondazione Cariplo
Good health and well-being
Openalex Percentile: Top 7%
Diabetes and associated disorders
DOIOpen Access PDFOpenAlex
AI Navigator

Ask Laika to Summarize, Analyze, and Connect papers live on the map.

Summarize Papers & Methodologies

Extract key findings, datasets, and comparative methods across publications.

Benchmark Rankings & Visual Analytics

Rank top research institutions, authors, funders, topics, and journals by Field-Weighted Citation Impact (FWCI) and paper volume with instant charts.

Connect Distant Disciplines

Bridge topological clusters on the map to find hidden collaborative intersections.