Introduction Psychological barriers to insulin therapy are associated with the delay of clinically indicated treatment intensification for people with type 2 diabetes (T2D), yet few evidence-based interventions exist to address these barriers. We describe the protocol for a randomised controlled trial (RCT) examining the efficacy of a novel, theoretically grounded, psychoeducational, web-based resource designed to reduce psychological barriers to insulin among adults with non-insulin treated T2D: ‘Is insulin right for me?’.

Methods and analysis Double-blind, parallel group RCT. A target sample of N=392 participants (n=196/arm) will be randomised (1:1) to ‘Is insulin right for me?’ (intervention) or widely available online resources (control). Eligible participants include adults (18–75 years), residing in Australia, currently taking oral hypoglycaemic agents to manage T2D. They will be primarily recruited via invitations and reminders from the national diabetes registry (from a purposefully selected sample of N≥12 000). Exclusion criteria: experience of self-administered injectable; previously enrolled in pilot RCT; ‘very willing’ to start insulin as baseline. Outcomes will be assessed via online survey at 2 weeks and 6 months. Primary outcome between-group: difference in mean negative Insulin Treatment Appraisal Scores (ITAS negative) at 2-week and 6-month follow-up. Secondary outcomes: between-group differences in mean positive insulin appraisals (ITAS positive) and percentage difference in intention to commence insulin at follow-up time points. All data analyses will be conducted according to the intention-to-treat principle.

Ethics and dissemination Deakin University Human Research Ethics Committee (2020–073). Dissemination via peer-reviewed journals, conferences and a plain-language summary.

Trial registration number ACTRN12621000191897; Australian and New Zealand Clinical Trials Registry.