Background: Communication of information about risk of type 2 diabetes (T2D) alone has not been associated with changes in habitual behaviors among individuals of European ancestry. In contrast, the use of wearable devices that monitor physical activity (PA) has been associated with changes in behavior in some studies. It is uncertain whether risk communication might enhance the effects of wearable devices. We aim to assess the effects on wearable-device-measured PA of communicating genetic risk for T2D alone or in combination with goal setting and activity prompts from a wearable device among overweight or obese East Asians.

Methods: In a parallel group, randomized controlled trial, a total of 355 overweight or obese East Asian individuals aged 40-60 years will be allocated into one of three groups: 1 control and 2 intervention groups. Blood samples will be used for estimation of T2D genetic risk and analysis of metabolic risk markers. Genetic risk of T2D will be estimated based on 113 SNPs associated with T2D among East Asians using an established method. All three groups will receive a Fitbit device. Both intervention groups will be given T2D genetic risk estimates along with lifestyle advice, but one of the intervention groups will additionally use Fitbit's step-goal setting and prompt functions. Questionnaires and physical measurements will be administered at baseline, immediately after intervention delivery, and 6 and 12-month post-intervention following standard operating procedures. The primary outcome is time spent in moderate-to-vigorous PA measured through the Fitbit. Secondary outcomes include other parameters of wearable-device-measured PA, sedentary time, and sleep, body mass index, systolic and diastolic blood pressure, five intermediate metabolic risk markers, hand grip strength, self-reported PA, self-reported fruit and vegetable consumption and smoking status, and a list of psychological variables.

Discussion: This study will be the first randomized controlled trial using the combination of communication of T2D genetic risk with standard functions of wearable devices in any population. Findings will inform strategies to prevent T2D through lifestyle modification.

Inclusion Criteria:

• East Asian ancestry
• Aged 40-60 years
• overweight or obese (i.e. measured BMI ≥23 kilograms/meters2 according to the WHO BMI-defined cut-offs for Asians)
• Able to perform daily-living physical activity
• using English/Chinese and a smartphone in Hong Kong

Exclusion Criteria:

• have been diagnosed with any type of diabetes
• pregnant or lactating
• unable to perform daily-life physical activities (determined through Physical activity Readiness Questionnaire [PAR-Q])
• participating in another research study or exercise programs
• had experience of genetic testing
• and/or cannot comprehend English/Chinese (i.e., sole language medium for the study).

The datasets analysed during the current study and statistical code are available from the corresponding author on reasonable request, as is the full protocol.

The datasets analysed during the current study and statistical code will be available after the completion of the study

IPD data can be accessed based on reasonable request by contacting the corresponding author.

Group allocation will be concealed from study staff until the 7-day pre-intervention period begins (for preparation of corresponding e-leaflets, genetic risk estimates and/or baseline Fitbit step goal calculations), and from participants until the interventions are delivered. Given the nature of the interventions delivered, it will be impossible for participants to be blinded to the specific intervention they receive once the initial interventions are provided; however, study staff analyzing participants' de-identified data will remain blinded to participant randomization assignment.