Introduction: Clusters of metabolic variables and their effects on incidence of type 2 diabetes have been studied previously; however, little is known about the effects on diabetes from risk factor clusters including lifestyle and self-rated health.
Hypothesis: We assessed the hypothesis that clusters of common cardiovascular risk factors, including lifestyle and self-rated health, can predict development of type 2 diabetes in men and women, respectively.
Methods: In 2002-2005, 2816 men and women, 30-74 years, were randomly selected from two municipalities in southwestern Sweden and assessed with regard to cardiovascular/metabolic risk factors within the Skaraborg Project (76% participation). Participants performed an OGTT, had blood samples drawn, had anthropometric measurements and blood pressure taken, and answered validated questionnaires about e.g. leisure-time physical activity (with four answer alternatives from intensive to sedentary) and self-rated health (with five alternatives from excellent to very poor). Using the same protocol, 1332 participants from the baseline survey where re-examined in 2011-2014. After excluding those with diabetes at baseline, 1268 participants were included in this prospective population-based study.
Results: Factor analysis (using varimax rotation) identified significant loadings (≥0.40) on the following three identical factors in men and women: the metabolic factor, comprising HOMA-ir, WHR, systolic blood pressure, and apolipoprotein B-to-A1 ratio; the vitality factor, comprising physical activity and self-rated health; and the addiction factor, comprising smoking and alcohol consumption. After a mean follow-up of 9.7±1.4 years, 76 cases of diabetes were identified; 46 in men and 30 in women. In a logistic regression analysis adjusted for all principal components, age, and educational level, the metabolic factor significantly predicted type 2 diabetes in both men (OR: 3.3, CI: 2.3-5.0) and women (OR: 3.5, CI: 2.2-5.6). Furthermore, a predictive effect of the vitality factor was also seen in women (OR: 1.8, CI: 1.2-2.9), but not in men (OR: 1.1, CI: 0.8-1.6), whereas the addiction factor had no effect in either men or women.
Conclusions: This is to our knowledge the first time principle components of cardiovascular risk factors, including both metabolic and lifestyle variables, have been used to predict incidence of type 2 diabetes. The gender difference observed with regard to the combined impact of self-rated health and physical activity are novel and indicates a mechanism beside the metabolic syndrome that warrants further gender-specific exploration in future studies.