High serum insulin, insulin resistance and their associations with cardiovascular risk factors The Northern Sweden MONICA population study

Abstract

Objectives. To estimate the prevalence of insulin resistance and high serum insulin levels and to investigate their relationship to other cardiovascular risk factors. Design. Cross-sectional cardiovascular risk factor survey. Setting. Northern Sweden. Subjects. A subsample of the population-based Northern Sweden MONICA Study. This subsample underwent an oral glucose tolerance test after an overnight fast, and consisted of 354 men and 404 women in the 25–64-year age range. Main outcome measures. Delineation of low insulin sensitivity and high serum insulin by the diagnostic test technique, prevalence of these variables and their associations with cardiovascular risk factors. Results. The participants were classified into four subgroups by an insulin sensitivity index and fasting serum insulin. The combination of low insulin sensitivity and high serum insulin was present in 17% of the male and in 18% of the female 25–64-year-old population. In both sexes this combination was closely associated (P < 0.001) with body mass index, waist-hip ratio, blood pressure and serum triglycerides, and correlated inversely with serum HDL cholesterol (P < 0.001). When high serum insulin was present as an isolated entity it was as closely associated with other cardiovascular risk factors such as isolated low insulin sensitivity, except that impaired glucose tolerance occurred exclusively in the group with isolated low insulin sensitivity. Conclusions. The combination of insulin resistance and high insulin levels is associated with a marked clustering of cardiovascular risk factors and is present in one-sixth of the middle-aged population in the north of Sweden.