Lifestyle Advice Combined with Personalized Estimates of Genetic or Phenotypic Risk of Type 2 Diabetes, and Objectively Measured Physical Activity: A Randomized Controlled Trial

Abstract

Background: Information about genetic and phenotypic risk of type 2 diabetes is now widely available and is being incorporated into disease prevention programs. Whether such information motivates behavior change or has adverse effects is uncertain. We examined the effect of communicating an estimate of genetic or phenotypic risk of type 2 diabetes in a parallel group, open, randomized controlled trial.

Methods and findings: We recruited 569 healthy middle-aged adults from the Fenland Study, an ongoing population-based, observational study in the east of England (Cambridgeshire, UK). We used a computer-generated random list to assign participants in blocks of six to receive either standard lifestyle advice alone (control group, n = 190) or in combination with a genetic (n = 189) or a phenotypic (n = 190) risk estimate for type 2 diabetes (intervention groups). After 8 wk, we measured the primary outcome, objectively measured physical activity (kJ/kg/day), and also measured several secondary outcomes (including self-reported diet, self-reported weight, worry, anxiety, and perceived risk). The study was powered to detect a between-group difference of 4.1 kJ/kg/d at follow-up. 557 (98%) participants completed the trial. There were no significant intervention effects on physical activity (difference in adjusted mean change from baseline: genetic risk group versus control group 0.85 kJ/kg/d (95% CI -2.07 to 3.77, p = 0.57); phenotypic risk group versus control group 1.32 (95% CI -1.61 to 4.25, p = 0.38); and genetic risk group versus phenotypic risk group -0.47 (95% CI -3.40 to 2.46, p = 0.75). No significant differences in self-reported diet, self-reported weight, worry, and anxiety were observed between trial groups. Estimates of perceived risk were significantly more accurate among those who received risk information than among those who did not. Key limitations include the recruitment of a sample that may not be representative of the UK population, use of self-reported secondary outcome measures, and a short follow-up period.

Conclusions: In this study, we did not observe short-term changes in behavior associated with the communication of an estimate of genetic or phenotypic risk of type 2 diabetes. We also did not observe changes in worry or anxiety in the study population. Additional research is needed to investigate the conditions under which risk information might enhance preventive strategies. (Current Controlled Trials ISRCTN09650496; Date applied: April 4, 2011; Date assigned: June 10, 2011).

Trial registration: The trial is registered with Current Controlled Trials, ISRCTN09650496.

Conflict of interest statement

The authors have declared that no competing interests exist.

Figures

Fig 1. Flow of participants through the DRCT.

Baseline characteristics were similar among the three study groups (Table 1). There were slightly more female (52.9%) than male participants. The mean (SD) age at which participants finished full-time education was 19.4 (4.4) y and most were employed full-time (68.0%). Overall, 10.6% were current smokers, and 26.8% consumed more than 11 units of alcohol per wk. Few participants were prescribed steroid or antihypertensive medication (5.8%) or had a positive family history for diabetes (23.0%). On average, participants were overweight (mean [SD] body mass index of 26.1 [4.2] kg/m2), but their HbA1c level was in the normal range (mean [SD] of 36.3 [4.4] mmol/mol).

Fig 2. Intervention effects on the primary outcome: physical activity.

Physical activity was defined as physical activity energy expenditure (kJ/kg/d) measured with a combined heart rate monitor and accelerometer. Plus–minus values are means ± standard error (SE). Analysis of covariance was used to assess differences between groups at follow-up, adjusted for baseline.