The Association Between Insulin Initiation and Adverse Outcomes After Hospital Discharge in Older Adults: a Population-Based Cohort Study

  • Zoe Lysy
  • Kinwah Fung
  • Vasily Giannakeas
  • Hadas D. Fischer
  • Chaim M. Bell
  • Lorraine L. LipscombeEmail author
Original Research



Starting insulin therapy in hospitalized patients may be associated with an increase in serious adverse events after discharge.


Determine whether post-discharge risks of death and rehospitalization are higher for older hospitalized patients prescribed new insulin therapy compared with oral hypoglycemic agents (OHAs).


Retrospective population-based cohort study including hospital admissions in Ontario, Canada, between April 1, 2004, and Nov 30, 2013.


Persons aged 66 and over discharged after a hospitalization and dispensed a prescription for insulin and/or an OHA within 7 days of discharge. We included 104,525 individuals, subcategorized into four mutually exclusive exposure groups based on anti-hyperglycemic drug use in the 7 days post-discharge and the 365 days prior to the index admission.

Main Measures

Prescriptions at discharge were categorized as new insulin (no insulin before admission), prevalent insulin (prescribed insulin before admission), new OHA(s) (no OHA or insulin before admission), and prevalent OHA (prescribed OHA only before admission) as the referent category. The primary and secondary outcomes were 30-day deaths and emergency department (ED) visits or readmissions respectively.

Key Results

Of 104,525 patients, 9.2% were initiated on insulin, 4.1% died, and 26.2% had an ED visit or readmission within 30 days of discharge. Deaths occurred in 7.14% of new insulin users, 4.86% of prevalent insulin users, 3.25% of new OHA users, and 3.45% of prevalent OHA users. After adjustment for covariates, new insulin users had a significantly higher risk of death (adjusted hazard ratio (aHR) 1.59, 95% confidence interval (CI) 1.46 to 1.74) and ED visit/readmissions (aHR 1.17, 95% CI 1.12 to 1.22) than prevalent OHA users.


Initiation of insulin therapy in older hospitalized patients is associated with a higher risk of death and ED visits/readmissions after discharge, highlighting a need for better transitional care of insulin-treated patients.


diabetes care transitions health services research 



We thank IMS Brogan Inc. for the use of their drug information database.


LL and ZL had the original idea for the study and contributed to the development of the data. HF, LL, ZL, and CB designed the study. KF and VG extracted data from the source database and validated the diagnostic codes from the database. ZL, KF, and VG undertook the statistical analysis. ZL reviewed the literature and wrote the first draft of the manuscript. LL co-drafted the manuscript and provided oversight for the project. CB, HF, and LL provided critical input to the analysis and design. All authors contributed to the critical review of the manuscript and approved its final submission. ZL and LL act as guarantors for the study.


Dr. Lipscombe is supported by a Diabetes Canada Investigator Award. This study was conducted with the support from a CIHR operating grant (MOP No. 123263). This study was supported by ICES, which is funded by an annual grant from the Ontario Ministry of Health and Long-Term Care (MOHLTC). The opinions, results and conclusions reported in this paper are those of the authors and are independent from the funding sources. No endorsement by ICES or the Ontario MOHLTC is intended or should be inferred.

Compliance with Ethical Standards

Conflict of Interest

The authors declare that they do not have a conflict of interest.

Ethics Approval

This project was approved by the Institutional Review Board at Sunnybrook Hospital.


Parts of this material are based on data and/or information compiled and provided by the Canadian Institute for Health Information (CIHI); however, the analyses, conclusions, opinions, and statements expressed in the material are those of the authors, and not necessarily those of CIHI.


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Copyright information

© Society of General Internal Medicine 2019

Authors and Affiliations

  • Zoe Lysy
    • 1
    • 2
  • Kinwah Fung
    • 3
  • Vasily Giannakeas
    • 1
    • 3
  • Hadas D. Fischer
    • 3
  • Chaim M. Bell
    • 2
    • 3
    • 4
    • 5
  • Lorraine L. Lipscombe
    • 1
    • 2
    • 3
    • 4
    Email author
  1. 1.Women’s College HospitalWomen’s College Research InstituteTorontoCanada
  2. 2.Department of MedicineUniversity of TorontoTorontoCanada
  3. 3.Institute for Clinical Evaluative SciencesTorontoCanada
  4. 4.Institute of Health Policy, Management and EvaluationUniversity of TorontoTorontoCanada
  5. 5.Sinai Health SystemTorontoCanada

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