Randomised controlled trial evaluating the effectiveness of behavioural interventions to modify cardiovascular risk factors in men and women with impaired glucose tolerance: outcomes at 6 months

Abstract

Aims: To evaluate the efficacy of interventions to promote a healthy diet and physical activity in people with impaired glucose tolerance (IGT).

Methods: A randomised controlled trial in Newcastle upon Tyne, UK, 1995-98. Participants included 67 adults (38 men; 29 women) aged 24-75 years with IGT. The intervention consisted of regular diet and physical activity counselling based on the stages of change model. Main outcome measures were changes between baseline and 6 months in nutrient intake; physical activity; anthropometric and physiological measurements including serum lipids; glucose tolerance; insulin sensitivity.

Results: The difference in change in total fat consumption was significant between intervention and control groups (difference -21.8 (95% confidence interval (CI) -37.8 to -5.8) g/day, P=0.008). A significantly larger proportion of intervention participants reported taking up vigorous activity than controls (difference 30.1, (95% CI 4.3--52.7)%, P=0.021). The change in body mass index was significantly different between groups (difference -0.95 (95% CI -1.5 to -0.4) kg/m(2), P=0.001). There was no significant difference in change in mean 2-h plasma glucose between groups (difference -0.19 (95% CI -1.1 to 0.71) mmol/l, NS) or in serum cholesterol (difference 0.02 (95% CI -0.26 to 0.31) mmol/l, NS). The difference in change in fasting serum insulin between groups was significant (difference -3.4 (95% CI -5.8 to -1.1) mU/l, P=0.005).

Conclusions: After 6 months of intensive lifestyle intervention in participants with IGT, there were changes in diet and physical activity, some cardiovascular risk factors and insulin sensitivity, but not glucose tolerance. Further follow-up is in progress to investigate whether these changes are sustained or augmented over 2 years.