The aim of this study was to investigate anthropometric and life-style determinants of insulinaemia. Specific fasting serum insulin (FI) was analysed in a general Caucasian population aged 50-74 years, not known to have diabetes mellitus (n = 2226, sample 1). The analysis was repeated some weeks later in a subgroup of sample 1 in which two individual measurements of FI were available (n = 540, sub-sample 2). Specific serum insulin 2 h after ingestion of 75 g glucose (2hI), also measured on two occasions, was analysed in this same subgroup after excluding 59 subjects with fasting plasma glucose >7 mmol l(-1) (n = 481, sub-sample 3). Multiple regression analyses were performed, stratified for sex, with 10log insulin as the dependent variable. All determinants were adjusted for each other. FI was positively associated with BMI and waist-hip ratio (men and women) and inversely associated with intake of fibre (women), moderate alcohol use (men), and current smoking (women). 2hI was positively associated with BMI and waist-hip ratio (men and women), and intake of fat (women). 2hI was inversely associated with physical activity and moderate alcohol use (men and women), and current smoking (men). Family history of diabetes was not associated with insulinaemia. In conclusion, various life-style factors are related to insulinaemia, independent of obesity.