Real-world effectiveness of digital and group-based lifestyle interventions as compared with usual care to reduce type 2 diabetes risk - A stop diabetes pragmatic randomised trial

Abstract

Background: No real-world randomised controlled trials (RCTs) have explored the effectiveness of lifestyle interventions based on multiple behaviour change theories and using combined digital and group-based face-to-face delivery to improve risk factors for type 2 diabetes (T2D).

Methods: We conducted a one-year, multi-centre, unblinded, pragmatic RCT in primary healthcare using the habit formation, self-determination, and self-regulation theories among 2907 adults aged 18-74 years at increased T2D risk randomised into a digital lifestyle intervention group (DIGI, n = 967), a combined digital and group-based lifestyle intervention group (DIGI+GROUP, n = 971), and a control group receiving usual care (CONTROL, n = 969). We collected data on primary outcomes (diet quality by Healthy Diet Index [HDI], physical activity, body weight, fasting plasma glucose, 2-hour plasma glucose) and secondary outcomes (sedentary time, waist circumference, fasting plasma insulin) using digital questionnaires, clinical examinations, fasting blood tests, and 2-hour oral glucose tolerance tests. Main statistical analyses were performed using linear mixed-effects models adjusted for age, sex, and province. This RCT was registered with ClinicalTrials.gov, NCT03156478.

Findings: The 2907 participants assigned were recruited between March 1^st, 2017, and February 28^th, 2018. Diet quality improved more (3·2 vs. 1·4 HDI points, p<0·001 for difference between groups, p'<0·001 for group*time interaction) and waist circumference tended to decrease more (-1·8 vs. -1·3 cm, p = 0·028, p' = 0·068) in DIGI+GROUP than in CONTROL. Fasting insulin tended to increase in CONTROL but not in DIGI (1·0 vs. 0·0 mU/L, p = 0·033, p' = 0·054) or in DIGI+GROUP (1·0 vs. 0·5 mU/L, p = 0·042, p' = 0·054). Good adherence to DIGI and DIGI+GROUP (≥median of 501 habits/year in DIGI, ≥5 of all 6 sessions in GROUP) was associated with improved diet quality and good adherence to DIGI with increased physical activity and decreased sedentary time.

Interpretation: A lifestyle intervention based on multiple behaviour change theories and combined digital and group-based face-to-face delivery improves diet quality and tends to decrease abdominal adiposity and prevent an increase in insulin resistance. Good adherence improves the results of the interventions.

Funding: Strategic Research Council at Academy of Finland, Academy of Finland, Novo Nordisk Foundation, and Finnish Diabetes Research foundation.

Keywords: Adiposity; Behaviour change; Diet; Digital; Habit formation; Insulin resistance; Lifestyle intervention; Nutrition; Physical activity; Prevention; Primary healthcare; Randomised controlled trial; Self-determination theory; Type 2 diabetes; eHealth.

Figure 1

Flow chart of the StopDia study.

Figure 2

Unadjusted one-year mean percentage changes in the Healthy Diet Index and its components in the control group (CONTROL), the digital intervention group (DIGI), and the combined digital and group-based face-to-face intervention group (DIGI+GROUP). The data are from linear mixed-effects models adjusted for age, sex, study province at baseline, and time between assessments (filling out questionnaires) and including the study group*time interaction term in these models. The asterisks denote the statistical significance (p<0·05) of the effects of DIGI and DIGI+GROUP on the Healthy Diet Index and its components compared with CONTROL. The P-values shown are for the statistical significance of the interaction effects between intervention and time (study group*time interactions) on the Healthy Diet Index and its components.

Figure 3

(a) Unadjusted one-year mean percentage changes in the Healthy Diet Index, physical activity, and sedentary time among those with high engagement in the digital intervention (≥median of 501 habits/year, higher 50%) and among those with low engagement in the digital intervention (<501 habits/year, lower 50%) in the study groups with digital intervention (DIGI and DIGI+GROUP). The data are from linear mixed-effects models adjusted for age, sex, study province at baseline, and time between assessments (filling out questionnaires). The P-values are for the statistical significance of the differences in the one-year mean percentage changes in the Healthy Diet Index, physical activity, and sedentary time between the low engagement group and the high engagement group. (b): Unadjusted one-year mean percentage changes in the Healthy Diet Index, physical activity, and sedentary time among those with low participation in both study interventions, high engagement in the digital intervention (≥501 habits/year, higher 50%), high attendance in the group-based face-to-face intervention (≥5 of all 6 group sessions), and high participation in both study interventions in the study group with group-based face-to-face intervention (DIGI+GROUP). The data are from linear mixed-effects models adjusted for age, sex, study province at baseline, and time between assessments (filling out questionnaires). The asterisks denote the statistical significance (p<0·05) of the differences in the one-year mean percentage changes in the Healthy Diet Index and sedentary time in the groups of high engagement in the digital intervention, high attendance in the group-based face-to-face intervention, and high participation in both interventions compared with the group of low participation in both interventions. The P-value shown is for the statistical significance of the difference in the one-year mean percentage change in the Healthy Diet Index across the groups of low participation in both interventions, high engagement in the digital intervention, high attendance in the group-based face-to-face intervention, and high participation in both interventions.