Obesity and risk factors for cardiovascular disease and type 2 diabetes: investigating the role of physical activity and sedentary behaviour in mid-life in the 1958 British cohort.

OBJECTIVE A key public health priority is to minimise obesity-related health consequences. We aim to establish whether physical activity (PA) or less sedentary behaviour ameliorate associations of obesity with biomarkers for cardiovascular disease (CVD) and type 2 diabetes. METHODS Data on obesity (33 y), PA (42 y), TV-viewing and health biomarkers (45 y) are from the 1958 British birth cohort (N=9377). RESULTS Obesity was associated with an adverse biomarker profile for CVD and type 2 diabetes. For PA, men active≥1/week had 1.09% (0.28, 1.90) lower diastolic blood pressure (DBP) than less active men; triglycerides were 2.08% (0.52, 3.64) lower per unit higher PA (on 4-point scale). TV-viewing was independently associated with several biomarkers, e.g. per unit higher TV-viewing (on 4-point scale) DBP was raised by 0.50% (0.09, 0.90) and triglycerides by 3.61% (1.58, 5.64). For both TV-viewing and PA, associations with HbA1c were greatest for the obese (pinteraction≤0.04): compared to a reference value of 5.20 HbA1c% in non-obese men viewing 0-1 h/day, HbA1c% differed little for those viewing>3 h/day; among obese men HbA1c% was 5.36 (5.22, 5.51) and 5.65 (5.53, 5.76), for 0-1 and >3 h/day respectively. For PA in non-obese men, the reduction associated with activity≥1/week was negligible compared to a reference value of 5.20 HbA1c% for those less active; but there was a reduction among obese men, HbA1c% was 5.50 (5.40, 5.59) vs 5.66 (5.55, 5.77) respectively. CONCLUSION Reduced TV-viewing and prevention of infrequent activity have greatest beneficial associations for glucose metabolism among the obese, with benefits for other biomarkers across obese and non-obese groups.