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Table 17 The relationship between physical activity and the development of type 2 diabetes.

From: A systematic review of the evidence for Canada's Physical Activity Guidelines for Adults

Publication Country Study Design Quality Score Objective Population Methods Outcome Comments and Conclusions
Haapanen et al 1997 [77] To examine the association of PA and the risk of CHD, hypertension and T2D. • n = 1,340 men, 1,500 women 10 yr follow-up Number of cases: 118 LTPA has a preventive effect on T2D.
   • Age: 35-63 yr PA assessment: Self-reported Age-adjusted RR (95% CI), men  
Finland    LTPA (kcal/wk), divided into groups • G1 = 1.54 (0.83-2.84)  
     • G2 = 1.21 (0.63-2.31)  
Prospective cohort     • G3 = 1.00 (referent)  
     p = 0.374  
    Men   
D & B score = 14    G1 = 0-1100 Age-adjusted RR (95% CI), women  
    G2 = 1101-1900 • G1 = 2.64 (1.28-5.44)  
    G3 = >1900 • G2 = 1.17 (0.50-2.70)  
     • G3 = 1.00 (referent)  
    Women (kcal/wk) p < 0.006  
    G1 = 0-900   
    G2 = 901-1500   
    G3 = >1500   
    Cox proportional HR   
Hu et al 2003 [111] To examine the relationship between sedentary behaviours (particularly prolonged television watching) and risk of obesity and T2D in women. • n = 68,497 (diabetes specific analyses) 6 yr follow-up Number of cases: 1515 Sedentary behaviours (especially television watching) are associated with an increased risk for obesity and T2D.
USA   • n = 50,277 (obesity specific analyses) PA assessment: Self-reported PA and sedentary behaviour Each 2-h/d increment in TV watching was associated with a 23% (95% CI, 17%-30%) increase in obesity and a 14% (95% CI, 5%- 23%) increase in risk of T2D  
Prospective cohort      
   • Age: 30-55 yr Outcome measure: onset of obesity and T2D Each 2-h/d increment in sitting at work was associated with a 5% (95% CI, 0%-10%) increase in obesity and a 7% (95% CI, 0%- 16%) increase in T2D Light to moderate PA was associated with a significantly lower risk for obesity and T2D.
D & B score = 13   • Sex: Women Multivariate analyses adjusting for age, smoking, dietary factors, and other covariates Standing or walking around at home (2 h/d) was associated with a 9% (95% CI, 6%-12%) reduction in obesity and a 12% (95% CI, 7%- 16%) reduction in T2D  
   • Characteristics:   Each 1 hour per day of brisk walking was associated with a 24% (95% CI, 19%-29%) reduction in obesity and a 34% (95% CI, 27%- 41%) reduction in T2D  
   Free of T2D, CVD, or cancer at baseline    
   • Nurses' Health Study    
Manson et al 1992 [112] To examine the association between regular exercise and the subsequent development of T2D. • n = 21,271 5 yr follow-up Number of cases: 285 Exercise appears to reduce the development of T2D even after adjusting for BMI.
   • Sex: Men PA assessment: Questionnaire Fpr VPA (enough to develop sweat)   
   • Age: 40-84 yr   The age-adjusted incidence of T2D:  
USA   • Characteristics:   • 369 cases per 100,000 person- years in men who engaged in VPA less than once weekly • 214 cases per 100,000 person- years in those exercising at least five times per week (p trend < 0.001)  
   Free of diagnosed diabetes, CVD and cancer at baseline    
Prospective cohort      
D & B score = 14    Exercise frequency (times/wk)   
    G1 = < Weekly   
    G2 = At least weekly   
     Age-adjusted RR (95% CI) by exercise frequency  
    Times per week   
    G1 = 0 • G1 = 1.00 (referent)  
    G2 = 1 • G2 = 0.64 (0.51- 0.82)  
    G3 = 2-4   
    G4 = >5 Age-adjusted RR (95% CI) by exercise frequency  
     • G1 = 1.00 (referent)  
    Outcome measure: Incidence T2D • G2 = 0.77 (0.55-1.07)  
     • G3 = 0.62 (0.46-0.82)  
     • G4 = 0.58 (0.40-0.84)  
     Age- and BMI-adjusted RR (95%  
     CI) by exercise frequency  
     • G1 = 1.00 (referent)  
     • G2 = 0.71 (0.56- 0.91)  
     Age- and BMI-adjusted RR (95% CI) by exercise frequency  
     • G1 = 1.00 (referent)  
     • G2 = 0.78 (0.56-1.09)  
     • G3 = 0.68 (0.51-0.90)  
     • G4 = 0.71 (0.49-1.03)  
Hu et al. 2001[114] To examine the relationship between dietary and lifestyle factors in relation to the risk for T2D. • n = 84,941 16 yr follow-up Number of cases: 3300 The majority of T2D could be prevented through healthy living.
   • Sex: Women    
   • Age: 40-75 yr PA assessment: Questionnaire For PA (h/wk), divided into groups Multivariate-adjusted RR (95%)  
USA   • Characteristics: participants had no history of diabetes, CVD, or cancer.   • Q1 = 1.00 (referent)  
     • Q2 = 0.89 (0.77-1.02)  
Retrospective cohort     • Q3 = 0.87 (0.75-1.00)  
    Q1 = <0.5 • Q4 = 0.83 (0.71-0.96)  
    Q2 = 0.5--1.9 • Q5 = 0.71 (0.56--0.90)  
D & B score = 13   Nurses' Health Study Q3 = 2.0--3.9   
    Q4 = 4.0--6.9   
    Q5 = ≥7.0   
    Outcome measure: Incidence of T2D   
    Cox regression   
Sato et al 2007 [116] To examine the relationship between walking to work and the development of T2D. • n = 8,576 4 yr follow-up Number of cases: 878 The duration of a walk to work is an independent predictor of the risk for T2D.
   • Sex: Men    
   • Age: 40--55 yr PA assessment: For time spent walking to work, divided into tertiles OR (95% CI)  
Japan   • Kansai Healthcare Study   • T1 = 1.00 (referent)  
     • T2 = 0.86 (0.70-1.06)  
Prospective cohort    T1 = 0-10 min • T3 = 0.73 (0.58-0.92)  
    T2 = 11-20 min Significant difference was seen between ≤ 10 min and ≤ 20 min only (p = 0.007)  
    T3 = ≥20 min   
D & B score = 14      
    Outcome measure: Incidence of T2D   
Hu G et al 2003 [117] To examine the relationship of OPA, commuting and LTPA with the incidence of T2D. • n = 14,290 PA assessment: Questionnaire For OPA, LTPA and commuting PA Multivariate adjusted HR (95% Cl) for OPA, men Moderate and high OPA, commuting PA or LTPA significantly reduces risk of T2D in middle aged adults.
   • Sex: Men and women    
     • G1 = 1.00 (referent)  
Finland   • Age: 35-64 yr   • G2 = 0.67 (0.44-1.01)  
   • Characteristic: OPA • G3 = 0.73 (0.52-1.02)  
Prospective cohort   Asymptomatic for stroke, CHD, or diabetes at baseline. G1 = Light (sitting)   
    G2 = Moderate (standing, walking) Multivariate adjusted HR (95% Cl) for OPA, women  
D & B score = 12    G3 = Active (walking, lifting) • G1 = 1.00 (referent)  
     • G2 = 0.72 (0.46-1.12)  
     • G3 = 0.78 (0.52-1.18)  
    Commuting PA (min/d)   
    G1 = None Multivariate adjusted HR (95% Cl) for OPA, men and women  
    G2 = 1-29   
    G3 = ≥ 30   
     G1 = 1.00 (referent)  
     G2 = 0.70 (0.52-0.96)  
    LTPA   
     G3 = 0.74 (0.57-0.95)  
    • G1 = Low (inactive)   
    • G2 = Moderate (walking, cycling >4 hr/wk)   
     Multivariate adjusted HR (95% Cl) for commuting PA, men  
    • G3 = High (running, jogging >3 hr/wk)   
     • G1 = 1.00 (referent)  
     • G2 = 1.00 (0.71-1.42)  
    Outcome measure: incidence of T2D • G3 = 0.75 (0.46-1.23)  
     Multivariate adjusted HR (95% Cl) for commuting PA, women  
    Cox proportional HR   
     • G1 = 1.00 (referent)  
     • G2 = 0.94 (0.63-1.42)  
     • G3 = 0.57 (0.34-0.96)  
     Multivariate adjusted HR (95% Cl) for commuting PA, men and women  
     • G1 = 1.00 (referent)  
     • G2 = 0.96 (0.74-1.25)  
     • G3 = 0.64 (0.45-0.92)  
     Multivariate adjusted HR (95% Cl) for LTPA, men  
     • G1 = 1.00 (referent)  
     • G2 = 0.78 (0.57-1.06)  
     • G3 = 0.84 (0.52-1.37)  
     Multivariate adjusted HR (95% Cl) for LTPA, women  
     • G1 = 1.00 (referent)  
     • G2 = 0.81 (0.58-1.15)  
     • G3 = 0.85 (0.43 -1.66)  
     Multivariate adjusted HR (95% Cl) for LTPA, men and women  
     • G1 = 1.00 (referent)  
     • G2 = 0.81 (0.64-1.20)  
     • G3 = 0.84 (0.57-1.25)  
Hsia et al 2005 [118] USA To evaluate the relationship between PA and the incidence of T2D in a large, diverse group of older women. • n = 87,907 PA assessment: Questionnaire for frequency and duration of 4 walking speeds and 3 other activities classified by intensity (light, moderate, strenuous) Number of cases: 2,271 There is a strong inverse relationship between PA and T2D. There is a stronger relationship between PA and T2D in Caucasian women than in minority women. This may be explained by less precise risk estimates in minority women.
   • Sex: Women    
   • Age: White 63.8 ± 7.3, African American 61.9 ± 7.3, Hispanic 60.5 ± 7.1, Asian/Pacific Islander 63.7 ± 7.6, American Indian 61.5 ± 8.0   Multivariate adjusted HR (95% CI) by walking, Caucasian  
     • Q1 = 1.00 (referent)  
Prospective cohort     • Q2 = 0.85 (0.74-0.87)  
     • Q3 = 0.87 (0.75-1.01)  
     • Q4 = 0.75 (0.64-0.89)  
D & B score = 11    Q1 = Low • Q5 = 0.74, (0.62-0.89)  
    Q2 = Trend p < 0.001  
    Q3 =   
    Q4 = Multivariate adjusted HR (95% CI) by TPA, Caucasian  
    Q5 = High   
   • Ethnicity: White n = 74,240; African American n = 6,465; Hispanic n = 3,231; Asian/Pacific Islander 2,445; American Indian n = 327   • Q1 = 1.00 (referent)  
    Cox proportional HR   
     • Q2 = 0.88 (0.76- 1.01)  
     • Q3 = 0.74 (0.64- 0.87)  
     • Q4 = 0.80 (0.68- 0.94)  
     • Q5 = 0.67 (0.56- 0.81) Trend p = 0.002  
   • Characteristics: participants had no history of diabetes, were not on any antidiabetic medications    
   • Women's Health Initiative    
Wannamethee et al 2000 [120] To examine the role of components of the insulin resistance syndrome in the relationship between PA and the incidence of T2D and CHD. • n = 5,159 16.8 yr follow-up Number of cases: 196 The relationship between PA and T2D appears to be mediated by serum insulin and components of the insulin resistance syndrome. However, these factors do not appear to explain the inverse relationship between PA and T2D.
   • Sex: Men    
   • Age: 40-59 yr PA assessment: Questionnaire for TPA Physical activity groups were identified and scored: Multivariate adjusted RR (95% CI)  
England, Wales and Scotland   • Characteristics: No history of heart disease, diabetes or stroke      Q1 = 1.00 (referent)  
        Q2 = 0.66 (0.42-1.02)  
        Q3 = 0.65 (0.41-1.03)  
Prospective cohort        Q4 = 0.48 (0.28-0.83)  
    Q1 = None    Q5 = 0.46 (0.27-0.79)  
    Q2 = Occasional p < 0.005  
D & B score = 14    Q3 = Light   
    Q4 = Moderate   
    Q5 = Moderately vigorous/vigorous   MPA (sporting activity once a week or frequent lighter- intensity activities such as walking, gardening, do-it yourself projects) are sufficient to produce a significant reduction in risk of both CHD and T2D.
    The men were classified according to current smoking status, alcohol consumption, and social class   
    Cox proportional HR   
Manson et al 1991 [121] To examine the association between regular VPA and the incidence of T2D. • n = 87,253 8 yr follow-up Number of cases: 1303 Women who engage in VPA at least once per week had reduced adjusted RR of T2D RR = 0.66 (0.6- 0.75) PA is promising in the primary prevention of T2D.
   • Sex: Women    
   • Age: 34-59 yr PA assessment:   
USA   • Characteristics: Free of diagnosed diabetes, cardiovascular disease and cancer Questionnaire   
    Frequency of weekly exercise (0-+4)   
Prospective cohort      
     The reduction in risk remained significant after adjustment for BMI RR = 0.84 (0.75-0.95)  
D & B score = 13    Analysis also restricted to the first 2 yr after the assessment of PA level and to symptomatic diabetes   
     When analysis was restricted to the first 2 years after ascertainment of PA level and to symptomatic disease as the outcome, the age- adjusted RR of those who exercised was 0.50, and age and body-mass index adjusted RR was 0.69 (0.48-1.0)  
    Multivariate adjustments for age, body-mass index, family history of diabetes, and other variables did not alter the reduced risk found with exercise   
    Multivariate analysis Family history of diabetes did not modify the effect of exercise, and risk reduction with exercise was evident among both obese and non-obese women  
Helmrich et al 1994 [122] To examine the relationship between PA and the development of T2D. • n = 5,990 98,524 man-years of follow-up (1962-1976) Number of cases: 202 Increased PA is effective in preventing T2D.
   • Sex: Men    
   • Age: 39-68 yr   RR (95% CI) by blocks walked per day  
USA   • Characteristics: healthy, asymptomatic PA assessment: Questionnaire for LTPA (walking, stair climbing, sports etc; kcal/wk) Blocks walked/day   The protective benefit is especially pronounced in those individuals who have the highest risk of disease.
        • T1 = 1.00 (referent)  
Further review of the data reported by Helmich et al. 1991        • T2 = 1.30  
   University of Pennsylvania Alumni Health Study      • T3 = 0.92  
     p = 0.80  
    LTPA (kcal/wk) kcal were assigned to each activity and added together LTPA was inversely related to the development of T2D  
Prospective cohort      
     Same findings to that reported in 1991  
D & B score = 14    Lowest < 500   
    Highest ≥ 3500   
    Blocks walked/day   
    T1 = <5   
    T2 = 5-14   
    T3 = ≥15   
    Cox proportional HR   
Helmrich et al 1991 [123] To examine the Relationship between PA and the Subsequent development of T2D. • n = 5,990 98,524 man-years of follow-up (1962-1976) Number of cases: 202 Increased PA is effective in preventing T2D.
   • Sex: Men    
   • Age: 39-68 yr   LTPA was inversely related to the development of type 2 diabetes  
USA   • Characteristics: healthy, asymptomatic PA assessment: Questionnaire for LTPA kcal/wk: stairs climbed/day and blocks walked/day, divided into groups   The protective benefit is especially pronounced in those individuals who have the highest risk of disease.
Prospective cohort     RR (95% CI) by sports played  
   • University of Pennsylvania Alumni Health Study   • G1 = 1.00 (referent)  
     • G2 = 0.90  
D & B score = 13     • G3 = 0.69  
     • G4 = 0.65  
    All activities LTPA Trend p = 0.02  
    Q1 = <500   
    Q2 = 500-999 RR (95% CI) by Flights of stairs climbed/day  
    Q3 = 1000-1499   
    Q4 = 1500-1999 • T1 = <5 = 1.00 (referent)  
    Q5 = 2000-2499 • T2 = 0.78  
    Q6 = 2500-2999   
     • T3 = 0.75  
    Q7 = 3000-3499   
     Trend p = 0.07  
    Q8 = ≥ 3500   
     RR (95% CI) by Blocks walked/day  
    Sports played   
     • T1 = 1.00 (referent0  
    G1 = None   
     • T2 = 1.31  
    G2 = Moderate   
    G3 = Vigorous • T3 = 0.93 Trend p = 0.80  
    G4 = Moderate and Vigorous   
     Age adjusted RR (95% CI) by all activities  
    Stairs climbed per day   
    T1 = <5 • Q1 = 1.00 (referent)  
    T2 = 5-14 • Q2 = 0.94  
    T3 = ≥ 15 • Q3 = 0.79  
     • Q4 = 0.78  
    Blocks walked per day • Q5 = 0.68  
    T1 = <5 • Q6 = 0.90  
    T2 = 5-14 • Q7 = 0.86  
    T3 = ≥ 15 • Q8 = 0.52  
     p = 0.01 for trend  
    Cox proportional HR   
     Age adjusted RR (95% CI) by all activities except vigorous sports  
     • Q1 = 1.00 (referent)  
     • Q2 = 0.97  
     • Q3 = 0.87  
     • Q4 = 0.92  
     • Q5 = 0.75  
     • Q6 = 1.29  
     • Q7 = 1.03  
     • Q8 = 0.48  
     Trend p = 0.07  
     Age adjusted RR (95% CI) by vigorous sports only  
     • Q1 = 1.00 (referent)  
     • Q2 = 0.69  
     • Q3 = N/A  
     • Q4 = 0.53  
     • Q5 = 0.86  
     • Q6 = 0.56  
     • Q7 = 0.40  
     • Q8 = 0.46  
     Trend p = 0.05  
Wei et al 1999 [124] To determine whether PF is associated with risk for impaired fasting glucose and T2D. • n = 8,633 6 yr follow-up Number of cases: 149 High PF is associated with a reduced risk for impaired fasting glucose and T2D.
USA   • Sex: Men    
   • Age: 43.5 yr PF assessment: Maximal treadmill exercise test (METs), divided into 3 groups 593 patients developed impaired fasting glucose  
   • Characteristics: Non-diabetic men   OR (95% CI) for developing glucose intolerance  
Prospective cohort    T1 = Low • T1 = 1.9 (1.5--2.4)  
    T2 = Moderate • T2 = 1.5 (1.2--1.8)  
    T3 = High • T3 = 1.00 (referent)  
D & B score = 12    Outcome measure: Incidence of impaired fasting glucose and T2D OR (95% CI) for developing T2D  
     • T1 = 3.7 (2.4 --5.8)  
     • T2 = 1.7 (1.1--2.7)  
     • T3 = 1.00 (referent)  
    Statistics: GLM   
Katzmarzyk et al 2007 [126] To examine the relationships among adiposity, PA, PF and the development of T2D in a diverse sample of Canadians. • n = 1,543 (709 men and 834 women) 6 yr follow-up Number of cases: 78 (37 in men, 41 in women) Adiposity and PF are important predictors of the development of T2D.
Canada   • Sex: Men and women PF assessment: Questionnaire PA was associated with 23% lower odds of developing diabetes and maximal METs was also associated with significantly lower odds of developing diabetes (OR = 0.28)  
Prospective cohort   • Age: 36.8 - 37.5 PA assessment: LTPA Questionnaire   
D & B score = 13   • Characteristics: Free of diabetes at baseline    
   • Canadian Physical Activity Longitudinal Study    
Burchfiel et al 1995 [345] To examine the relationship between PA and T2D. • n = 6,815 6 yr follow-up Number of cases: 391 PA is associated inversely and independently with incident T2D.
USA   • Sex: Men (Japanese- American) PA assessment: Questionnaire PA index (based on intensity and duration of activity) The age-adjusted 6-year cumulative incidence of diabetes decreased progressively with increasing quintile of physical activity from 73.8 to 34.3 per 1,000 (p < 0.0001, trend)  
   • Age: 45-68 yr Levels of activity:   
Prospective cohort   • Characteristics: Free of diabetes at entry Q1 = Basal - Sleeping reclining   
D & B score = 13   • The Honolulu Heart Program Q2 = Sedentary   
    Q3 = Slight - Casual walking   
    Q4 = Moderate -- Gardening   
    Q5 = Heavy - Lifting, shoveling   
    Outcome measure: Self-reported T2D (clinically recognized)   
Dziura et al 2004 [346] To determine the prospective relation between reports of habitual PA, 3-year change in body weight, and the subsequent risk of T2D in an older cohort. • n = 2,135 PA assessment: Questionnaire for 4 types of activities (walking, gardening/housework, physical exercises, active sports or swimming) and frequency of participation measured with a PA score: 118 cases of T2D Observation of an inverse relationship between reported PA and rate of T2DM.
USA   • Sex: Men and women   Incident density of T2D = 6.6/1000 person years  
   • Age: ≥ 65 yr    
Prospective cohort   • Ethnicity: 83% White, 15% African American, 2% Non-white   Diabetes (n = 118) PA score: 2.17 ± 1.7 'Some' PA: 78% Subjects reporting some PA at baseline experienced a rate of T2D over 50% lower relative to those reporting no PA.
D & B score = 12   • Characteristics: Healthy asymptomatic Never (score 0) Sometimes (score 1) Often (score 2) Non-Diabetes (n = 2017) PA score: 2.34 ± 1.7 'Some' PA: 84%  
    Pearson product moment correlation coefficient and Cox proportional HR   
Hu et al. 1999 [347] To quantify the dose-response relationship between total PA and incidence of T2D in women. • n = 70,102 8 yr of follow-up Number of cases: 1419 Increased PA is associated with substantial reduction in risk of T2D including PA of moderate intensity and duration.
USA   • Sex: Women PA assessment: Questionnaire for TPA (MET hr/wk) and VPA (6 METs) Multivariate-adjusted RR (95% CI) of by TPA  
   • Age: 40-65 yr   • Q1 = 1.0 (referent)  
Prospective cohort To examine the health benefits of walking in comparison to more vigorous activity. • Characteristics: participants had no history of diabetes, CVD, or cancer TPA (MET hr/wk) • Q2 = 0.77 (0.66-0.90)  
D & B score = 12   Nurses' Health Study Q1 = 0-2.0 • Q3 = 0.75 (0.65-0.88)  
    Q2 = 2.1-4.6 • Q4 = 0.62 (0.52-0.73)  
    Q3 = 4.7-10.4 • Q5 = 0.54 (0.45-0.64)  
    Q4 = 10.5-21.7 Trend p < 0.001  
    • Q5 = ≥ 21.8   
    MET score Multivariate-adjusted RR (95% CI) among women who did not perform vigorous exercise (MET's):  
    Q1 = ≤ 0.5 • Q1 = 1.0 (referent)  
    Q2 = 0.6-2.0 • Q2 = 0.91 (0.75-1.09)  
    Q3 = 2.1-3.8 • Q3 = 0.73 (0.59-0.90)  
    Q4 = 3.9-9.9 • Q4 = 0.69 (0.56-0.86)  
    Q5 = ≥ 10.0 • Q5 = 0.58 (0.46-0.73)  
    Outcome measures: Trend p < 0.001  
    Incidence of T2D   
Hu et al 2001 [348] To examine the role of prolonged television watching on the risk for T2D. • n = 37,918 10 year follow-up Number of cases: 1058 Increasing PA is associated with a significant reduction in risk for T2D, whereas a sedentary lifestyle indicated by prolonged TV watching is related directly to increased risk.
USA   • Sex: Men    
   • Age: 40-75 yr PA assessment: Questionnaire for PA (MET hr/wk) and TV watching (h/wk), each divided into quintiles Multivariate-adjusted RR (95% CI) by PA  
Prospective cohort   • Characteristics: participants had no history of diabetes, CVD, or cancer Q1 = 0-5.9 • Q1 = 1.00 (referent)  
D & B score = 11   • Health Professionals' Follow-up Study Q2 = 6.0-13.7 • Q2 = 0.78 (0.66 -- 0.93)  
    Q3 = 13.8-24.2 • Q3 = 0.65 (0.54 -- 0.78)  
    Q4 = 24.3-40.8 • Q4 = 0.58 (0.48 -- 0.70)  
    Q5 = ≥ 40.9 • Q5 = 0.51 (0.41 -- 0.63)  
     Trend p < 0.001  
    Time spent watching television per week (h/wk) Multivariate-adjusted RR (95% CI) by TV time  
    Q1 = 0-1 • Q1 = 1.00 (referent)  
    Q2 = 2-10 • Q2 = 1.66 (1.15 - 2.39)  
    Q3 = 11-20 • Q3 = 1.64 (1.12 - 2.41)  
    Q4 = 21-40 • Q4 = 2.16 (1.45 - 3.22)  
    Q5 = >40 • Q5 = 2.87 (1.46 - 5.65)  
     Trend p < 0.001  
Rana et al 2007 [349] To examine the individual and combined association of obesity and physical inactivity with the incidence of T2D. • n = 68,907 16 yr follow-up Number of cases: 4,030 This study found that obesity and physical inactivity independently contributed to the development of T2D.
USA   • Sex: Women    
Prospective cohort   • Age: 30-55 years age range in 1976 (note: 1986 was the baseline year for the study) PA assessment: Questionnaire for average amount of time/week MET hours per week spent in MVPA (≥ 3 METs), divided into quintiles Multivariate-adjusted RR (95% CI) by MVPA: The benefits of PA were not limited to lean women; among those who were overweight and obese, physically active women tended tobe at lower risk for T2D than sedentary women.
D & B score = 12   • Characteristics: No history of diabetes, CVD or cancer Q1 = <2.1 • Q1 = 2.37 (2.15--2.16)  
   • Nurses' Health Study Q2 = 2.1-4.6 • Q2 = 1.92 (1.73--2.13)  
    Q3 = 4.7-10.4 • Q3 = 1.48 (1.34--1.64)  
    Q4 = 10.5-21.7 • Q4 = 1.40 (1.26--1.55)  
    Q5 = ≥ 21.8 • Q5 = 1.00 (referent)  
     Trend p < 0.001  
    Cox proportional HR   
Sawada et al 2003 [350] To examine the association between PF and the incidence of T2D. • n = 4,747 14 yr follow-up Number of cases: 280 Low PF is associated with a higher risk for the development of T2D.
Japan   • Sex: Men    
   • Age: 20-40 yr PF assessment: Maximal aerobic power estimate ml/kg/min using a submaximal cycle ergometer test, divided into quartiles Age-adjusted RR (95% CI)  
Prospective cohort   • Characteristics: Free of diabetes, CVD, hypertensin, tuberculosis, and gastrointestinal disease at baseline Q1 = 32.4 ± 3.1 • Q1 = 1.00 (referent)  
D & B score = 13    Q2 = 38.0 ± 2.5 • Q2 = 0.56 (0.42-- 0.75)  
    Q3 = 42.4 ± 3.0 • Q3 = 0.35 (0.25-- 0.50)  
    Q4 = 51.1 ± 6.2 • Q4 = 0.25 (0.17-- 0.37)  
     Trend p < 0.001  
    Outcome measure: Incidence of T2D Multivariate adjusted RR (95% CI)  
     • Q1 = 1.00 (referent)  
     • Q2 = 0.78 (0.58--1.05)  
     • Q3 = 0.63 (0.45--0.89)  
     • Q4 = 0.56 (0.37--0.84)  
     Trend p = 0.001  
    Cox proportional HR   
Weinstein et al 2004 [351] To examine the relative contributions and joint association of PA and BMI with T2D. • n = 37,878 6.9 year follow up Number of cases: 1,361 Although BMI and physical inactivity are independent predictors of incident diabetes, the magnitude of the association with BMI was greater than with PA in combined analyses. These findings underscore the critical importance of adiposity as a determinant of T2D.
USA   • Sex: Women PA assessment: Questionnaire for walking per week (h/wk) and TPA (kcal/wk), divided into groups and quartiles respectively Multivariate-adjusted HR (95% CI) by time spent walking  
   • Age: 45+ years   • G1 = 1.00 (referent)  
Prospective cohort   • Health care professionals   • G2 = 0.95 (0.82-1.10)  
D & B score = 12   • Characteristics: No history of CVD, cancer or diabetes   • G3 = 0.87 (0.73 -1.02)  
     • G4 = 0.66 (0.54-0.81)  
     • G5 = 0.89 (0.73-1.09)  
    Walking per week (h/wk) Trend p = 0.004  
    G1 = no walking Multivariate-adjusted HR (95% CI) by TPA  
    G2 = <1 • Q1 = 1.00 (referent)  
    G3 = 1-1.5 • Q2 = 0.91 (0.79-1.06)  
    G4 = 2-3 • Q3 = 0.86 (0.74-1.01)  
    G5 = ≥ 4 • Q4 = 0.82 (0.70-0.97)  
    TPA (kcal/wk) Trend p = 0.01  
    Q1 < 200   
    Q2 = 200-599   
    Q3 = 600-1,499   
    Q4 ≥ 1500   
    Cox proportional HR   
  1. D & B score, Downs and Black quality score; YR, years; PA, physical activity; CHD, coronary heart disease; T2D, type 2 diabetes; LTPA, leisure-time physical activity; g, group; kcal/wk, kilocalories per week; HR, hazard ratio; RR, risk ratio; OR, odds ratio; 95% CI, confidence interval; CVD, cardiovascular disease; OPA, occupational physical activity; PF, physical fitness; MET, metabolic equivalent; MET/wk, metabolic equivalent per week.