Table 17.

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

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

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.