Grauslund 2009.

Study characteristics
Methods	Study design: prospective cohort longitudinal Location: Denmark Time period: baseline 1981 to 82; follow‐up 2007 to 2008 Outcome: PDR Outcome measurement: incidence and OR (95% CI)
Participants	Number of participants: 573 Diabetes type: T1D Inclusion criteria: all T1D patients from Fyn County, Denmark, with DM onset before 30 years of age, identified based on insulin prescription as of 1 July 1973 Exclusion criteria: not reported
Notes	Link to data extraction table, risk of bias assessment, and results: osf.io/ef7w9/?view_only=6fd044128cb14a4592c3df877f0507bc
Item	Authors' judgement	Support for judgement
Study participation	Unclear	See ‘Notes’ above for link to risk of bias assessment
Study attrition	Unclear	See ‘Notes’ above for link to risk of bias assessment
Prognostic factor measurement	Unclear	See ‘Notes’ above for link to risk of bias assessment
Outcome measurement	Yes	See ‘Notes’ above for link to risk of bias assessment
Adjustment for other prognostic factors	Unclear	See ‘Notes’ above for link to risk of bias assessment
Statistical analysis and reporting	Unclear	See ‘Notes’ above for link to risk of bias assessment