RELATIONSHIP BETWEEN THE CHANGES IN PHYSICAL ACTIVITY AND PLASMA INSULIN DURING A 2.5-YEAR FOLLOW-UP 181

The association between the changes in physical activity (PA) and fasting plasma insulin level was analysed in a 2.5-year follow-up study of 146 men, aged 50 to 60 years. PA was assessed by a 7-day PA recall interview, and plasma insulin radioimmunologically. Total PA decreased from 45.1 (SD 10.1) to 39.0 (6.1) METh·day-1 and conditioning PA (cPA, > 5.0 METs) from 8.0 (11.2) to 2.7 (5.0) METh·day-1, whereas plasma insulin increased from 8.2 (5.8) to 9.2 (6.7) mU·l-1 and body weight(BW) from 80.5 (12.0) to 81.6 (11.6) kg during the follow-up (p≤0.001 for all). The change (Δ) in cPA correlated inversely (r=-0.34, p<0.001) and the ΔBW positively (r=0.42, p<0.001) with the change in plasma insulin level. With data adjusted for the baseline insulin level, and cardiovascular health status, alcohol intake, ΔBW, smoking, age and follow-up time, the odds ratio for an increase in fasting plasma insulin level during the follow-up was 8.86 (95%CI 2.12; 37.11, p=0.003) for the men with the greatest decrease in cPA (>7 METh) as compared to those who reported an increase in cPA. The same logistic regression model showed an odds ratio of 9.86 (2.14; 45.35, p=0.003) for those who had gained more than 3.3 kg of BW as compared to those who had lost ≥ 0.6 kg. The men who consumed alcohol ≥ 12 g·day-1 at both examinations had an odds ratio of 12.84(1.74; 94.48, p=0.012) as compared to non-drinkers. These data suggest that, in middle-aged men, reduction in physical activity increases the risk for an increase in plasma insulin level independently of alcohol consumption and changes in body weight.