BACKGROUND: Long-term conditions (LTCs) are the biggest contributor to health loss in New Zealand. The economic cost and burden on the health system is substantial and growing. Self-management strategies offer a potential way to reduce the pressure on health services. This study evaluates a comprehensive self-management programme (the BetaMe programme) delivered by mobile and web-based technologies for people with Type 2 diabetes (T2DM) and pre-diabetes. The primary aim of this study is to evaluate the effectiveness of the BetaMe programme versus usual care among primary care populations in improving the control of T2DM and pre-diabetes, as measured by change in HbA1c and weight over 12 months. METHODS: Participants will be recruited through two primary healthcare organisations and a Māori healthcare provider in New Zealand (n = 430). Eligible participants will be 18 to 75 years old, with T2DM or pre-diabetes, with an HbA1c of 41-70 mmol/mol up to 2 years prior to study commencement. Eligible participants who consent to participate will be individually randomised to the control arm (usual care) or intervention arm (usual care and BetaMe). The programme consists of a 16-week core followed by a maintenance period of 36 weeks. It incorporates (1) individualised health coaching, (2) goal setting and tracking, (3) peer support in an online forum and (4) educational resources and behaviour-change tools. The primary outcome measures are change in HbA1c and weight at 12 months. Secondary outcomes are changes in waist circumference, blood pressure, patient activation and diabetes-specific behaviours. All outcomes will be assessed at 4 and 12 months for the total study population and for Māori and Pacific participants specifically. All primary analyses will be based on intention-to-treat. Primary analysis will use linear mixed models comparing mean outcome levels adjusted for initial baseline characteristics at 12 months. DISCUSSION: This is a randomised controlled trial of a comprehensive self-management intervention for people with diabetes and pre-diabetes. If effective, this programme would allow healthcare providers to deliver an intervention that is person-centred and supports the self-care of people with T2DM, pre-diabetes and potentially other LTCs. TRIAL REGISTRATION: Australian New Zealand Clinical Trials Registry, ID: ACTRN12617000549325 . Registered on 19 April 2017.