Table 1.

Measures used in the Diabetes Risk Communication Trial (DRCT)

Measure(s)	Brief description	Stage assessed
		Fenland study	DRCT baseline	DRCT post- intervention	DRCT follow-up
Demographic characteristics		Sex, age, race/ethnicity, immigrant status, level of education, employment status, and level of income were assessed through self-report.	✓
Anthropometric, body composition, clinical, physical activity, biochemical, medical history, and lifestyle	Anthropometric (e.g., height, weight, hip and waist), body composition (e.g., precise body fat percentage and distribution using ultrasound and DEXA), clinical (e.g., blood pressure and pulse rate), and physical activity measurements (e.g., heart rate, movement, and oxygen consumption at rest and during a sub-maximal treadmill test) were assessed by trained staff. An oral glucose tolerance test was administered, and two blood samples were taken to assess glucose levels and blood lipids. Medical history and general lifestyle were assessed through self-report.	✓
Perceived healthy weight	Participants are asked what they think a healthy weight is for them in either stones or kilograms. This measure has been used in previous research [66].		✓
Perceived weight status	Participants are asked if they think that they are underweight, overweight, or an acceptable weight. This measure has been used in previous research [67,68]		✓
Perception of diet	1) Participants are asked how much fruit and vegetables they think that they eat compared to people of their age and sex, and answer on a 5-point response scale, ranging from “much less” to “much more”. 2) Participants are asked whether or not they meet the national recommendations for fruit and vegetable consumption. Similar measures have been used in previous research [69,70].		✓
Perception of physical activity	1) Participants are asked how physically active they think that they are compared to people of their age and sex, and answer on a 5-point response scale, ranging from “much less” to “much more”. 2) Participants are asked whether or not they meet the national guidelines for engagement in physical activity. Similar measures have been used in previous research [71,72].		✓
History of genetic testing	Participants are asked if they have ever had a genetic test to assess their risk of developing a disease, and if so, to list the disease(s) for which their risk was assessed.		✓
Process measures	Participants are asked what they think that their risk estimate showed, how accurate they think that their risk estimate is, whether or not they have kept their risk estimate, and whether or not they have discussed their risk estimate with someone. Additionally, participants are asked if they previously had a genetic test to assess their risk of developing a disease, and if so, to list the disease(s) for which their risk was assessed.				✓
Diabetes risk representations*	Assessed using the Brief Illness Perceptions Questionnaire (Brief IPQ) [73]. The Brief IPQ consists of 8 items that address the cognitive and emotional illness representations in the CSM. To capture representations of T2D risk held by healthy individuals, the items have been adapted according to methods used in previous research [74,75]. The Brief IPQ has been shown to have good test-retest reliability and to be highly correlated with relevant subscales of the IPQ-R [73].		✓	✓
Self-efficacy, response efficacy, and perceived severity*	Assessed using 10 Likert items. Each item includes a statement (e.g., “I am confident that I could be more physically active if I wanted to”) evaluated on a 5-point response scale, ranging from “strongly disagree” to “strongly agree”. These items have been adapted for use in the context of T2D [76,77] and have been used in previous research [78].		✓	✓
Perceived risk*	1) Participants are asked how likely they think that they are to get T2D in the next 10 years and their lifetime, and first answer on a 5-point response scale, ranging from “very unlikely” to “very likely”, and then on a continuous scale, ranging from 1 to 100. 2) Participants are asked how likely they think they are to get T2D in the next 10 years and their lifetime, compared to people their same age and sex, and answer on a 5-point response scale, ranging from “much less likely” to “much more likely”. These items have been adapted according to recommendations provided by Diefenbach et al. [79], and have been used in previous research [80].		✓	✓	✓
Self-rated health*	Participants are asked if they think that their overall health is excellent, good, fair, or poor. This measure has been used in previous research [81].		✓		✓
Diabetes-related worry*	Assessed using the Cancer Worry Scale (CWS) [82]. The CWS consists of 6 items that assess the frequency of worries about developing cancer and the effect that these worries have on mood and daily functioning. These items have been adapted for use in the context of T2D and have been shown to have acceptable test-retest reliability and good internal consistency [83].		✓		✓
Anxiety*	Assessed using the short-form of the state scale of the Spielberger State Trait Anxiety Inventory (STAI) [84]. The short-form STAI consists of 6 items that comprise the most highly correlated anxiety-present and anxiety-absent items from the full-form of the STAI. Scores obtained using this short-form have been shown to be highly correlated with scores obtained using the full-form of the STAI [84].		✓	✓	✓
Intentions to be physically active and engage in a healthy diet*	Assessed using 4 items. Each item includes a statement (e.g., “I intend to be more physically active in the next 8 weeks.”) evaluated on a 5-point response scale, ranging from “extremely unlikely” to “extremely likely”. These items have been adapted according to recommendations provided by Ajzen [77] and have been used in previous research [78,85].		✓	✓	✓
Self-reported weight*	Participants are asked what their current weight is, without shoes, in either stones or kilograms. Detailed descriptions of the reliability and validity of self-reported weight have been published elsewhere [86].		✓		✓
Self-reported diet*	Assessed using the Food Frequency Questionnaire (FFQ) [87]. The FFQ contains a list of 130 foods, including 12 fruit items and 26 vegetable items. Only the fruit and vegetable items are assessed at follow-up. Detailed descriptions of the reliability and validity of the FFQ have been published elsewhere [87,88].	✓			✓

*Secondary outcomes.