Fasting insulin at baseline influences the number of cardiometabolic risk factors and R-R interval at 3years in a healthy population: the RISC Study

Aim: This was a cross-sectional and longitudinal study of factors contributing to the number of cardiometabolic risk factors, common carotid artery intima-media thickness (CCA-IMT) and R-R interval in clinically healthy subjects without diabetes.

Methods: Anthropometric and cardiometabolic parameters were measured in the Relationship between Insulin Sensitivity and Cardiovascular Disease (RISC) Study cohort at baseline (n=1211) and 3years later (n=974). At baseline, insulin sensitivity was assessed by the euglycaemic clamp technique. The CCA-IMT was echographically measured and the R-R interval was electrocardiographically evaluated at baseline and at the 3-year follow-up.

Results: Higher baseline BMI, fasting insulin and tobacco use as well as greater changes in BMI and fasting insulin but lower adiponectin levels, were associated with a greater number of cardiometabolic risk factors at the 3-year follow-up independently of insulin sensitivity (all P<0.02). The CCA-IMT increased with the number of cardiometabolic risk factors (P=0.008), but was not related to fasting insulin, whereas higher fasting insulinaemia and its 3-year changes were significantly associated with a smaller R-R interval (P=0.005 and P=0.002, respectively). These relationships were independent of baseline age, gender, BMI, adiponectin, insulin sensitivity, tobacco use and physical activity.

Conclusion: In clinically healthy subjects, fasting insulinaemia, adiponectin and lifestyle parameters are related to the presence of one or two cardiometabolic risk factors before criteria for the metabolic syndrome are met. These results underline the importance of fasting insulinaemia as an independent cardiometabolic risk factor at an early stage of disease development in a healthy general population.