Table 1.
Study characteristics.
| Author(s)(year) CountryIntervention | Study design | Comparison group(s) | Study duration | Enrolment setting | Definition of high risk of T2D | Sample (intervention group) | Attrition (intervention group) |
|---|---|---|---|---|---|---|---|
| Aguiar et al.(2016)Australia | Randomised Controlled Trial | Waitlist control | 6 months | University | Australian Diabetes Risk Tool (AUSDRISK) score of ≥12.BMI: 25–40 kg/m2 | n = 53Age range: 20–65 yearsMean age: 52.5 ± 9.5 yearsMale: 100%Ethnicity: not reportedMean BMI: 32.2 ± 3.5 kg/m2 | 9.4% at 3 months24.5% at 6 months |
| Arens et al. (2018)Germany | Prospective observational study | Usual care | 12 months | Primary care | Presence of metabolic syndrome. | n = 109Age range: 35–60 yearsMean age: 49.6 ± 9.3 yearsFemale: 60.6%Ethnicity: not reportedMean BMI: 32.2 ± 5.5 kg/m2 | 19.3% at 3 months32.1% at 6 months49.5% at 9 months79.8% at 12 months |
| Block et al.(2015)USA | Randomised Controlled Trial | Waitlist control | 6 months | Primary care | Presence of prediabetesBMI: ≥27 kg/m2 (≥25 kg/m2 for Asian subgroups).Fasting glucose: 100–125 mg/dLA1c: 5.7–6.4%. | n = 163Age range: 31–70 yearsMean age: 55 ± 8.8 yearsMale: 68.1%White: 66.9%Mean BMI: 31.1 ± 4.5 kg/m2 | 16.6% at 6 months |
| Castro Sweet et al. (2018)USA | Single-arm prospective study | NA | 12 months | Online | Presence of prediabetes (A1c: 5.7–6.4%). Metabolic syndrome (Prediabetes, hypertension, dyslipidaemia and obesity). | n = 501Age range: not reportedMean age: 68.8 ± 2.6 yearsFemale: 64%White: 60.3%Mean BMI: 33.6 ± 5.7 kg/m2 | 4% of participants did not meet CDC DPRP criteria (as they completed ≤3 intensive phase lessons). |
| Cha et al.(2014)USA | Single-arm prospective pilot study | NA | 12 weeks | University | Presence of prediabetes (impaired fasting glucose: 100–125 mg/dL; or, A1c: 5.7–6.4%). | Intervention completers:n = 13Age range: 21–28 yearsMean age: 24.4 ± 2.2 yearsFemale: 76.9%African American: 53.8%Mean BMI: not reported | 13.3% at 12 weeks |
| Estabrooks and Smith-Ray (2008)USA | Randomised Controlled Trial | Usual care | 3 months | Primary care | Elevated blood glucose and/or clinical diagnosis of prediabetes. | n = 39Age range: not reportedMean age: 57.8 ± 17 yearsFemale: 71.8%White: 69%Mean BMI: not reported | 28.2% at 3 months |
| Everett et al. (2018)USA | Single-arm prospective observational study | Calibration cohort | 3 months | University hospital | Diagnosis of prediabetes (fasting glucose: 100–125 mg/dL; impaired glucose tolerance: 2-hour glucose of 140–199 mg/dL after 75g oral glucose tolerance test; or, A1c: 5.7–6.4%).BMI: 24–40 kg/m2 (22–40 kg/m2 for Asian individuals). | Intervention completers only:n = 38Age range: not reportedMean age: 57.2 ± 9.1 yearsFemale: 63%White: 82%Mean BMI: not reported | 11.6% at 3 months |
| Fischer et al. (2016)USA | Randomised Controlled Trial | Usual care | 12 months | Primary care | A1c between 5.7% and 6.4%. | n = 78Age range: not reportedMean age: 47.7 ± 12.4Female: 70.5%Native Spanish speakers: 65%Mean BMI: not reported | 7.7% at 12 months |
| Fukuoka et al.(2015)USA | Feasibility Randomised Controlled Trial | Pedometer only control | 5 months | Primary care | BMI: ≥25 kg/m2 (22 kg/m2 if Asian-Pacific Islander).American Diabetes Association Diabetes Risk Test score of ≥5. Fasting plasma glucose: 100–125 mg/dL; A1c: 5.7–6.4%; Oral glucose tolerance test: 140–200 mg/dL. | n = 30Age range: 36–76 yearsMean age: 57.1 ± 9.1 yearsFemale: 76.7%White: 43.3%Mean BMI: 32.2 ± 5.6 kg/m2 | 10% of participants did not complete 3-month follow-up assessment. 6.6% of participants did not complete 5-month follow-up assessment. |
| Kramer et al. (2010)USA | Non-randomised Controlled Trial | Face-to-face intervention | 3 months | Primary care | BMI ≥25 kg/m2Prediabetes (Fasting glucose: 100–125 mg/dL).Presence of metabolic syndrome. | n = 22Age range: not reportedMean age: 57.3 yearsSex/gender: not reportedEthnicity: not reportedMean BMI: 32.9 ± 6.1 kg/m2 | 36.4% at 3 months |
| Limaye et al. (2017)India | Randomised Controlled Trial | Standard care | 12 months | Worksite | Presence of ≥3 risk factors (family history of cardio-metabolic disease, overweight/obesity, high blood pressure, impaired fasting glucose, Hypertriglyceridaemia, high LDL and low HDL cholesterol). | n = 133Age range: not reportedMean age: 36.8 ± 7.2 yearsMale: 74.4%Ethnicity: not reportedMean BMI: 27 ± 3.2 kg/m2 | 21.1% at 12 months |
| Ma et al. (2013)USA | Randomised Controlled Trial | Coach-led intervention; usual care control | 15 months | Primary care | BMI: ≥25 kg/m2Prediabetes (fasting plasma glucose: 100–125 mg/dL) Metabolic syndrome (central obesity, dyslipidaemia, hypertension, prediabetes). | n = 81Age range: not reportedMean age: 51.8 ± 9.9 yearsMale: 54.3%White: 79%Mean BMI: 31.7 ± 4.7 kg/m2 | 7.4% at 15 months |
| Michaelides et al. (2016)USA | Single-arm prospective study | NA | 24 weeks(plus 65 week follow-up) | Worksite | Hyperglycaemia (A1c: 5.7–6.4%). | Program starters: n = 43Age range: not reportedMean Age: 51.5 ± 8.3 yearsFemale: 86%Ethnicity: not reportedMean BMI: 35.5 ± 7.4 kg/m2 | 16.3% of program starters (read >1 article per week for ≥4 weeks) did not complete the core program. |
| Piatt et al.(2013)USAGLB-DVD | Prospective quasi-experimental study | Face-to-face; internet; self-selection interventions | 6 months(plus 18 month follow-up) | University | BMI: ≥25 kg/m2Abdominally obese (waist circumference: >40 inches in males and >25 inches in females). | n = 113Age range: not reportedMean age: 52.4 ± 10.9 yearsFemale: 85%White: 93.8%Mean BMI: 36.2 ± 7.2 kg/m2 | 43.4% at 6 months |
| Piatt et al.(2013)USAGLB-Internet | Prospective quasi-experimental study | Face-to-face; DVD; self-selection interventions | 6 months(plus 18 month follow-up) | University | BMI: ≥25 kg/m2Abdominally obese (waist circumference: >40 inches in males and >25 inches in females). | n = 101Age range: not reportedMean age: 48.7 ± 9.7 yearsFemale: 88.1%White: 99.1%Mean BMI: 36.1 ± 6.4 kg/m2 | 56.4% at 6 months |
| Ramachandran et al. (2013)India | Randomised Controlled Trial | Usual care | 24 months(plus five year follow-up) | Worksite | Positive family history of T2D.BMI: ≥23 kg/m2 | n = 271Age range: not reportedMean age: 54.1 ± 6.1 yearsMale: 100%Ethnicity: not reportedMean BMI: 25.8 ± 3.3 kg/m2 | 3.7% at 24 months |
| Sepah et al. (2014)USA | Quasi-experimental Single-arm prospective study | NA | 12 months (plus 24 and 36 month follow-ups) | Online | BMI: ≥25 kg/m2 (22 kg/m2 if Asian). | Core group:n = 187Age range: not reportedMean age: 43.9 ± 12.4 yearsFemale: 85%White: 51%Mean BMI: 36.7 ± 7.6 kg/m2 | 15% of participants did not meet CDC DPRP ‘core phase’ criteria (as they only completed ≤3 core lessons). 34.5% did not meet ‘post-core phase’ criteria (completed ≤3 core lessons and 0 post-core lessons) |
| Tate et al.(2003)USABasic Internet | Randomised Controlled Trial | Internet and Behavioural e-Counselling Intervention | 12 months | University hospital | BMI between 27–40 kg/m2≥1 risk factors for T2D (e.g., family history of T2D, impaired glucose tolerance). | n = 46Age range: not reportedMean age: 47.3 ± 9.5 yearsFemale: 89%White: 89%Mean BMI: 33.7 ± 3.7 kg/m2 | 15.2% at 12 months |
| Tate et al.(2003)USAInternet and Behavioral e-Counseling | Randomised Controlled Trial | Basic Internet Intervention | 12 months | University hospital | BMI between 27–40 kg/m2≥1 risk factors for T2D (e.g., family history of T2D, impaired glucose tolerance). | n = 46Age range: not reportedMean age: 49.8 ± 9.3 yearsFemale: 91%White: 89%Mean BMI: 32.5 ± 3.8 kg/m2 | 17.4% at 12 months |
| Wilson et al.(2017)USA | Non-randomised controlled observational study | Matched control | 2 years | Worksite | BMI: ≥24 kg/m2 (22 kg/m2 if Asian); Prediabetes (fasting blood glucose: 100–125 mg/dL, A1c: 5.7–6.4%, oral glucose tolerance test: 140–199 mg/dL). | n = 634Age range: 23–68 yearsMedian age: 46 yearsFemale: 58.4%White: 68%Mean BMI: 34.5 kg/m2 | 5.8% of participants did not meet CDC DPRP criteria (completed ≤3 intensive phase lessons). 76% of participants had sufficient data for analysis. |
| Wong et al. (2013)Hong Kong | Randomised Controlled Trial | Usual care | 24 months | University hospital | Diagnosis of prediabetes (fasting plasma glucose: 5.6–6.9 mmol/L; or, 2-hour postprandial glucose: 7.8–11.0 mmol/L after 75g glucose load). | n = 54Age range: not reportedMean age: 54.1 ± 6.1 yearsMale: 90.7%Ethnicity: not reportedMean BMI: 25.6 ± 2.9 kg/m2 | 16.7% at 12 months24.1% at 24 months |
NA: Not Applicable.