Methods

Follow‐up: 1 year.
Number study arms: 2: exercise+diet and control group; number of participants randomised to each group: 187 randomised to I2 and 188 to CG..
Setting: Asti (Northwesten Italy).
Number of study centres: NR.
Language of publication: English.
ITT analysis: N.
Per‐protocol analysis: Y.

Participants

Randomised number: I2:187, CG: 188
Analysed number: I2: 169, CG: 166.
Age (years): I2: 55.7(5.7); C1: 55.7(5.6)

Sex (% female): I2: 58.6; C1: 57.8

Baseline BMI: I2: 29.7(4.1); C1: 29.8(4.6)

Inclusion criteria: age: 45‐64 years
metabolic syndrome or two components of metabolic syndrome plus high‐sensitivity CRP (hs‐CRP) serum values ≥3 mg/L, the cutoff point that differentiates high‐risk groups for future cardiovascular events.

Exclusion criteria: Diseases which require specific diet and exercise recommendations: diabetes, cardiovascular diseases, chronic liver or kidney disease and advanced cancer

Ethnic group: NR.
BL comparable: Yes.

Interventions

Duration of intervention: 1 year.
Intervention groups:
I2: Family physician advice plus detailed verbal and written recommendation including individually prescribed diet and advise on exercise mainly by suggesting moderate‐intensity activity, such as brisk walks for ar least 150 minutes/week. Sessions had a flexible structure, sensitive to cultural differences and patient expectations.
CG: family physician advice emphasizing on the importance of a healthy lifestyle according to their usual clinical practice.
Behavioral intervention: NR.
Frecuency: NR.
No. of contacts: 5.
Group/Individual: Individual.
Medium: In person.
Facilitator: nutritionists, specialists in endocrinology and internal medicine.

Outcomes

Primary outcomes: IDM
Secondary outcomes: IFG, FPG, W, BMI, Waist, TG, HDL, Chol, SBP, DBP,

Notes

Stated aim of study: To know wether a program of moderate intervention might effectively reduce metabolic abnormalities in the general population.

Randomization procedure: performed by using an SAS program stratifying participants according to sex, education level, general practitioner, area of residence, and number of metabolic syndrome components.
Allocation concealment: Yes.
Attrition (%): 11
Blinding assessor: Yes.

Risk of bias

Bias

Authors' judgement

Support for judgement

Adequate sequence generation?

Low risk

Quote: "Participants were stratified according to age, sex, education level..."

"the randomisation procedure was automatically performed by a statistician using a SAS programme developed to minimize the differences between the two groups for all stratifying variables."

Allocation concealment?

Low risk

Quote: "Random allocation with a minimization algorithm was centrally performed in a single step. The researchers then received the two lists of nominative data."

Blinding?
All outcomes

Low risk

Quote: "Because of the nature of the intervention, blinding participants and health professionals was not possible. Family physicians, the physicians who collected data, the dietician, and the laboratory personnel were blinded to the group assignment."

Incomplete outcome data addressed?
All outcomes

Low risk

Quote: "Written informed consent to participate was not given by 18 of 187 (9.6%) and 22 of 188 (11.7%) subjects from the intervention group and the control group, respectively."

Free of selective reporting?

Unclear risk

Comment: Insufficient information provided.

Free of other bias?

Low risk

Methods

Follow‐up: 6 years.
Number study arms: 4: exercise ‐only, exercise+diet, diet‐only and control group; number of participants randomised to each group: NR.
Setting: Chinese community.
Number of study centres: 33 health care clinics.
Language of publication: English.
ITT analysis: trial authors stated: Yes.
Per‐protocol analysis: Yes.

Participants

Randomised number: 577.
Analysed number: I1 141, I2: 126, I3: 130, CG: 133.
Age (years):45.0 (9.1).
Sex (% female): 47.0.
Baseline BMI: 25.8 (3.8).
Inclusion criteria: 2h PG glucose>=120 mg/dl (6.7 mmol/L) and <200 mg/dl (11.0 mmol/L), followed by 2h OGTT (WHO 1985).
Exclusion criteria: NR.
Ethnic group: Asian.
BL comparable: Yes.

Interventions

Duration of intervention: 6 years.
Intervention groups:
I1: encouraged to increase the amount of physical exercise; duration dependent on intensity.
I2: instructions and counseling similar to those for diet only and exercise only intervention groups.
I3: reducing energy intake: diet and diet+exercise groups: if BMI <25, 25‐30 kcal/kg with 55‐65% carbohydrate,10%‐15% protein, 25%‐30% fat; if BMI>25, goal to lose 0.5 to 1.0 kg/month until BMI = 23 kg/m2.
CG: general instructions for diet and/or increased leisure physical activities.
Behavioral intervention: NR.
Frecuency: both diet and exercise interventions: counselling sessions weekly for 1 month, monthly for 3 months, and then once every 3 months.
No. of contacts: 30.
Group/Individual: Both.
Medium: In person.
Facilitator: Physician and team.

Outcomes

Primary outcomes: IDM
Secondary outcomes: FPG, 2h PG, M

Notes

Stated aim of study: to determine whether diet and exercise interventions in those with IGT may delay the development of DM.
Randomization procedure: by clusters, method of randomisation: NR.
Allocation concealment: NR .
Attrition (%):8. Blinding assessor: NR.

Risk of bias

Bias

Authors' judgement

Support for judgement

Adequate sequence generation?

Unclear risk

Quote: "subjects were randomised by clinic"

Allocation concealment?

Unclear risk

Comment: no information

Blinding?
All outcomes

Unclear risk

Comment: no information

Incomplete outcome data addressed?
All outcomes

Unclear risk

Quote: "7 people refused follow‐up, 29 left Da Qing..., and 11 died... No deaths... occurred in the exercise... Three deaths occurred in the control..."

"Those who left in 1988 very early in the study and before the first follow‐up for reasons unrelated to their randomisation group were not included in the analysis. The 11 who died were retained, although none had developed diabetes before death."

Free of selective reporting?

Unclear risk

Comment: insufficient information provided.

Free of other bias?

High risk

Quote: "Physical exercise, expressed in units per day, was significantly higher at baseline in the diet‐plus exercise group than in the control group."

Methods

Follow‐up: average 2.8 years; range 1.8‐4.6.
Number study arms: 3: lifestyle (exercise+diet),
metformin (not reported here) and control group (standard recommendation+placebo): 1079 randomised to I2 and 1082 to CG.
Setting: USA.
Number of study centres: 27.
Language of publication: English.
ITT analysis: Yes.
Per‐protocol analysis: No.

Participants

Randomised number: 3234
Analysed number: I2: 1079, CG: 1082.
Age (years): 50.6 (10.7).
Sex (% female): 67.7.
Baseline BMI: 34.0 (6.7).
Inclusion criteria: >=25 years, BMI>=24 in Asians BMI>=22, FPG 95‐125 mg/dl (5.3‐6.9 mmol/L) and 2‐h OGTT
140‐199 mg/dl (7.8‐11.0 mmol/L) (ADA 1997).
Exclusion criteria: participants taking medicines known to alter glucose tolerance or if they had illnesses that could seriously reduce their life expectancy or their ability to participate in the trial.
Ethnic group: White (54.7%), African American (19.9%), Hispanic (15.7%), American Indian (5.3%), Asian (4.4%).
BL comparable: Yes.

Interventions

Duration: Average 2.8 years, range 1.8‐4.6
Intervention groups: I2: physical activity intervention: moderate‐intensity exercise for
150 min a week; supervised group exercise sessions twice a week were offered.
Dietary intervention: goal 7% weight loss through a healthy low‐calorie, low‐fat diet.
CG: written information and annual 30 min
individual session on healthy lifestyles.
Behavioral intervention: culturally sensitive materials and motivational strategies.
Frequency: 16 lessons in first 24 weeks, then monthly.
No.of contacts:40
Group/individual: both.
Medium: In person.
Facilitator: Case manager ("lifestyle coach"), usually a dietitian.

Outcomes

Primary outcomes: IDM, CVD
Secondary outcomes: FPG, W, BMI, WHR, Waist, SBP, DBP, Cost

Notes

Stated aim of study: to evaluate whether a lifestyle‐intervention program or the administration of metformin would prevent or delay the development of diabetes.
Randomisation procedure: adaptive randomisation.
Allocation concealment: NR
Attrition (%): 8.
Blinding assessor: Yes.

Risk of bias

Bias

Authors' judgement

Support for judgement

Adequate sequence generation?

Unclear risk

Quote: "adaptative randomisation is stratified by clinical centre"

Allocation concealment?

Low risk

Quote: "The urn method was used"

Blinding?
All outcomes

Low risk

Quote: "Investigators and participants remain masked to primary outcome data until progression to diabetes is confirmed." "Assignments to metformin and placebo were double‐blinded"

Incomplete outcome data addressed?
All outcomes

Low risk

Quote: "Participants who prematurely discontinue their follow‐up visits before confirmed development of diabetes will be censored as of their last follow‐up visit."

Free of selective reporting?

Unclear risk

Comment: Outcomes published in many different publications. Many outcomes are reported incompletely so that they cannot be entered in a meta‐analysis.

Free of other bias?

Low risk

Methods

Follow‐up: 3.2 years.
Number study arms: 2: exercise plus diet and control group: 265 randomised to I2 and 257 to CG.
Setting: Finland.
Number of study centres: 5.
Language of publication: English.
ITT analysis: stated yes by the trial authors.
Per‐protocol analysis: Yes.

Participants

Randomised number: 522.
Analysed number: I2: 256, CG: 250.
Age (years): 55 (7.0).
Sex (%female): 67.0.
Baseline BMI: 31.1 (4.6)
Inclusion criteria: BMI>=25; IGT (2‐h post prandial plasma glucose 140‐200 mg/dl [7.8‐11.0 mmol/L ]) and FPG <140mg/dl (7.8 mmol/L) (WHO 1985), 40‐65 years.
Exclusion criteria: diagnosis of diabetes mellitus, chronic disease, psychological or physical disabilities deemed likely to interfere with participation in the study.
Ethnic group: NR.
BL comparable: Yes.

Interventions

Duration of intervention: mean 3.2 years.
Intervention group:
I2: Individual counseling regarding moderate activity 30 minutes / day; supervised strength training; frequency and availability varied among study centers.
Dietary intervention:
Low fat, high‐fiber diet; goal BMI <25 or 5‐10kg weight loss; <50%
carbohydrate,<30% fat,<300 mg / day cholesterol.
CG: general written and oral information to prevent DM at baseline and annually.
Behavioral intervention: food records; goal setting.
Frecuency: 7 sessions with dietitian first year, then every 3 months.
No. of contacts: 15.
Group/Individual: individual.
Medium: In person.
Facilitator: physician, nurse, nutritionist, physiotherapist.

Outcomes

Primary outcomes: IDM
Secondary outcomes: FPG, 2h PG, W, BMI, Waist, TG, HDL, Chol, SBP, DBP, Cost,

Notes

Stated aim of study: to assess the efficacy of an intensive diet‐exercise programme in preventing or delaying Type II DM in individuals with IGT.
Randomization procedure: using a list, stratified by center, sex, and 2h PG value.
Allocation concealment: NR .
Attrition (%): 8. Blinding assessor: Yes.

Risk of bias

Bias

Authors' judgement

Support for judgement

Adequate sequence generation?

Unclear risk

Quote: "randomization list, with stratification according to center, sex and mean 2hPG.

Allocation concealment?

High risk

Quote: "randomly assigned to the intervention group or the control group by the study physician, with the use of a randomization list"

Blinding?
All outcomes

Low risk

Quote: "The nurses who scheduled the study visits did not have access to the randomization list... Laboratory staff did not know the subjects' group assignments, and the subjects were not informed of their plasma glucose concentrations during follow‐up unless diabetes was diagnosted."

Incomplete outcome data addressed?
All outcomes

Low risk

Quote: "...were defined as dropouts... data from their earlier visits were included in the analyses."

"40 subjects (8 percent) withdrew ‐ 23 in the intervention group and 17 in the control group... 9 could no tbe contacted, 3 withdrew due to severe ilness, 1 died, and 27 withdrew for personal reasons."

Free of selective reporting?

Unclear risk

Comment: Insufficient information provided.

Free of other bias?

Low risk

Methods

Follow‐up: mean 30 months.
Number study arms: 4: exercise+diet defined as lifestyle modification (LSM), metformin group (not reported here), LSM+metformin (not reported here), and control group: 133 randomised to I2 and 136 to CG.
Setting: India.
Number of study centers: NR.
Language of publication: english.
ITT analysis: No.
Per‐protocol analysis: Yes.

Participants

Randomised number: 531.
Analysed number:
I2: 120, I3: 129, I4: 133, CG: 136.
Age (years): 45.9
Sex (%female): 21
Baseline BMI: 25.8
Inclusion criteria: IGT: mean 2‐h post prandial plasma glucose 140‐199 mg/dl [7.8‐11.0 mmol/L] and FPG <126mg/dl (7.0 mmol/L) (WHO 1999).
Exclusion criteria: diagnosis of DM during recruitment.
Ethnic group: Asian Indian.
BL comparable: Yes.

Interventions

Duration of intervention: 3 years.
Intervention groups:
I2: physical activity intervention: participants involved in exercise regularly were to ask to continue their routine activities. Sedentary or light physical activity participants encouraged to physical activity at least 30 min/day.
Dietary intervention: reduction in total calories, refined carbohidrates and fats, inclusion of fiber‐rich foods.
CG: standard health care advice.
Behavioral intervention: motivational strategies.
Frequency: every 6 months.
No.of contacts: 6.
Group/individual: individual.
Medium:In person.
Facilitator: physician dietician and social worker.

Outcomes

Primary outcomes: IDM
Secondary outcomes: FPG, 2h PG, W, BMI, WHR, Chol, HDL, LDL, TG, SBP, DBP, M

Notes

Stated aim of study: tested whether the progression to diabetes could be influenced by interventions in native Asia Indians with IGT.
Randomization procedure: NR.
Allocation concealment: NR .
Attrition (%): 6.
Blinding assessor: the principal investigators were blinded to interim results.

Risk of bias

Bias

Authors' judgement

Support for judgement

Adequate sequence generation?

Unclear risk

Quote: "were consecutively randomised in the four groups"

Allocation concealment?

Unclear risk

Comment: no information

Blinding?
All outcomes

Low risk

Quote: "The principal investigators were blinded to the interim results."

Incomplete outcome data addressed?
All outcomes

Low risk

Comment: Lost to follow‐up and drop outs described in a flow chart.

Free of selective reporting?

Unclear risk

Comment: Insufficient information provided.

Free of other bias?

Low risk

Methods

Follow‐up: 4 years.
Number study arms: 2:
Intensive intervention group (intervention group) and
standard intervention group (control group): 102 randomised to I2 and 356 to CG.
Setting: Japan.
Number of study centers: NR.
Language of publication: english.
ITT analysis: NR.
Per‐protocol analysis: Yes.

Participants

Randomised number: 484.
Analysed number: I2: 102, CG: 356.
Age (years): 51.5 (NR).
Sex (% female): 0.
Baseline BMI: 23.9 (2.2)
Inclusion criteria: FPG<140 mg/dl and a 2‐h PG value between 160 and 239 mg/dl on 100 g OGTTs; the individuals had IGT according to the WHO criteria in 1980.
Exclusion criteria: Known DM, diagnosed or suspected malignant neoplasm, diagnosed or suspected disease of the liver, pancreas, endocrine organs, or kidney; ischemic heart disease or cerebrovascular disease.
Ethnic group: Asian.
BL comparable: Yes.

Interventions

Duration of intervention: 4 years.
Intervention group:
I2: physical activity: walking 30‐40 min/day or 30 min cycling in weekends was recomended.
advised to lose weight if BMI >=22 Kg/m2 by eating smaller meals
(reduce amount about 10%), reduce consume of fat‐rich foods.
CG: advised to lose weight if BMI >=24 Kg/m2 taking 5–10% smaller meals, and to increase their physical activity.
Behavioral intervention: encourage cooperation of the family members, goal setting.
Frequency: every 6 months for controls and 3‐4 months for intervention group.
No.of contacts: 8.
Group/individual: individual.
Medium: In person.
Facilitator: NR.

Outcomes

Primary outcomes:
IDM
Secondary outcomes:
W

Notes

Stated aim of study: to assess the effect of lifestyle intervention on the incidence of diabetes in males with IGT. Randomization procedure: one of every five persons was randomly selected for allocating to the I2, and the others were assigned to the CG.
Allocation concealment: NR .
Attrition (%): 13.
Blinding assessor: NR.

Risk of bias

Bias

Authors' judgement

Support for judgement

Adequate sequence generation?

Unclear risk

Quote: "One of every five subjects was randomly selected for allocation the intensive intervention group, and the others were assigned to the standard intervention (control) group."

Allocation concealment?

Unclear risk

Comment: no information

Blinding?
All outcomes

Unclear risk

Comment: no information

Incomplete outcome data addressed?
All outcomes

Unclear risk

Comment: no reasons for missing data provided.

Free of selective reporting?

Unclear risk

Comment: insufficient information provided.

Free of other bias?

Low risk

Methods

Follow‐up: 24 months.
Number study arms:2: I2: Live style(exercise+diet), CG: No lifestyle advise: 37 randomised to I2 and 32 randomised to CG.
Setting: UK.
Number of study centres: 1.
Language of publication: English.
ITT analysis: Yes.
Per‐protocol analysis: No.

Participants

Randomised number: 78
Analysed number: I2: 37, CG: 32 at 6 month; I2: 32, CG: 30 at 12 month; I2: 30, CG: 24 at 24 month
Age(years): I2: 58 (41‐75); CG: 57 (41‐73)
Sex(%female): 43
Baseline BMI: I2: 30.4 (5.6); CG: 29.9 (4.9)
Inclusion criteria: IGT (2‐h post glucose load plasma glucose 140‐200 mg/dL [7.8‐11.0 mmol/L]) (WHO 1985);
24‐75 years.
Exclusion criteria: Pregnant individuals, on therapeutic diets or whose medical condition prevent them from undertaking moderate physical activity.
Ethnic group: White.
BL comparable: Yes.

Interventions

Duration: 24 month.
I2: Physical activity intervention: graded plan, tailored to the participants lifestyle and designed to enable them to achieve 20‐30 min of aerobic activity al least once a week. CITY CARD is provided, offering up to 80% discount on use of public leisure facilities.
Diet intervention: Reduce BMI to <25 in overweight; <=30 % of energy from fat; polyunsaturated to saturated fat ratio >=1.0; 50% from carbohydrate; >=20g per 4.2MJ dietary fibre intake.
CG: No intervention.
Behavioral intervention: motivational interviewing to develop an individual action plan for behaviour change.
Frequency: first 6 months 3 appointments at 2 weekly intervals, followed by 3 at monthly intervals. One after 9 months and 5 at 2 monthly intervals between 12 and 24 months.
No. of contacts: 12
Group/Individual: Individual.
Medium: In person.
Facilitator: Dietitian and physiotherapist.

Outcomes

Primary outcomes: IDM
Secondary outcomes: FPG, 2h PG, W, BMI, WHR, Waist, TG, HDL, LDL, Chol, SBP, DBP, M

Notes

Stated aim of study: To evaluate the efficacy of interventions to promote a healthy diet and physical activity in people with impaired glucose tolerance.
Randomization procedure: using a random number table to the intervention or control group.
Allocation concealment: YES (not clear if adequate)
Attrition (%): 31
Blinding assessor: NR

Risk of bias

Bias

Authors' judgement

Support for judgement

Adequate sequence generation?

Low risk

Quote: "...using a random number table to the intervention or control group at the first appointment."

Allocation concealment?

Low risk

Quote: "Researchers performing the randomisation were blinded to the group allocation."

Blinding?
All outcomes

Unclear risk

Comment: no information.

Incomplete outcome data addressed?
All outcomes

High risk

Comment: there was a high attrition rate, not balanced between treatment groups. Attrition rate was 23% in the treatment group and 38% in the control group after 24 month of follow‐up.

Free of selective reporting?

Unclear risk

Comment: insufficient information.

Free of other bias?

High risk

Quote: "...a significantly larger proportion of control participants reported engaging in regular physical activity sufficient to get their heart thumping at least once a week compared with intervention participant (53% versus 24%)"

"There were fewer women (10/32 (32%)) than men (22/32 (69%)) in the control group compared with the intervention group..."

Methods

Follow‐up: 2 years.
Number study arms: 4: exercise, exercise+diet, diet and control group: 37 randomised to I1, 40 to I2, 37 to I3 and 40 to CG.
Setting: USA.
Number of study centres: NR.
Language of publication: English.
ITT analysis: NR
Per‐protocol analysis: Yes.

Participants

Randomised number: 154.
Analysed number: I1: 31, I2: 32, I3: 35, CG: 31, at 2 years.
Age (years):45.7 (4.4).
Sex (% female): 79
Baseline BMI: 35.9 (4.3).
Inclusion criteria: overweight subjects (30–100% of ideal body weight), aged 40–55 years, nondiabetic, and had one or two biological parents with DM.
Exclusion criteria: NR.
Ethnic group: NR.
BL comparable: Yes.

Interventions

Duration of intervention: 2 years.
Intervention groups:
I1: encouraged to increase physical activity (e.g., walking 3 miles on each of 5 days in the week) in biweekly increments of 250 Kcal/week to achieve a goal of 1500 Kcal/week.
I2: instructions and counselling similar to those for diet only and exercise only intervention groups.
I3: reducing energy intake: 800–1,000 kcal/day, 20% of calories as fat, for weeks 1–8 then 1,200–1,500 kcal/day at week 16; both the diet and exercise interventions received behavioral therapy.
CG: general written and oral information to lose weight and exercise on their own.
Behavioral intervention: food records for feedback, individualization, motivational strategies.
Frecuency: I1, I2, I3: weekly for the first 6 months, and then biweekly meetings for 6 months, then two 6‐week refresher courses during year 2.
No. of contacts: 51.
Group/Individual: Group.
Medium: In person.
Facilitator: nutritionist, exercise physiologist, behavior therapist.

Outcomes

Primary outcomes: IDM
Secondary outcomes: FPG, W, BMI, WHR, TG, HDL, LDL, Chol, SBP, DBP

Notes

Stated aim of study: to determine the effectiveness over 2 years of diet, exercise, or the combination of diet + exercise on changes in eating and exercise behavior, body weight, cardiovascular risk factors, and the incidence of diabetes in overweight individuals with a parental history of DM.
Randomization procedure: NR.
Allocation concealment: NR.
Attrition (%): 15% at 6 month, 22% at 1 year and 16% at 2 years.
Blinding assessor: NR.

Risk of bias

Bias

Authors' judgement

Support for judgement

Adequate sequence generation?

Unclear risk

Quote: "...were randomly assigned to one of the four treatment conditions."

Allocation concealment?

Unclear risk

Comment: no information.

Blinding?
All outcomes

Low risk

Quote: "All scoring of the 3‐day records was done blinded to treatment condition and phase"

Incomplete outcome data addressed?
All outcomes

Unclear risk

Comment: no information on reasons for missing data provided.

Free of selective reporting?

Unclear risk

Comment: insufficient information provided.

Free of other bias?

Low risk