THE RELATIONSHIP BETWEEN SERUM LIPOPROTEIN(A) AND INSULINEMIA IN WEALTHY NONDIABETIC ADULT MEN

OBJECTIVE- To test the hypothesis that variations in serum insulin con centrations and insulin action may influence serum concentrations of l ipoprotein(a) [Lp(a)]. RESEARCH DESIGN AND METHODS- A cross-sectional analysis of fasting serum insulin and Lp(a) concentrations were conduc ted in a group of 54 healthy adult men 23-61 years of age. Measures of dietary intake, exercise, smoking, alcohol ingestion, body mass index (BMI), fasting plasma lipoprotein lipid concentrations, and serum sex hormone and fasting glucose levels were also determined. RESULTS- The fasting serum concentrations of insulin and Lp(a) were negatively cor related (r = -0.339, P = 0.014) by univariate regression analysis. Sev eral confounding variables were also significantly correlated with Lp( a) concentrations: testosterone (r = 0.348, P = 0.012), strenuous exer cise (r = 0.287, P = 0.041), and BMI (r = -0.276, P = 0.050). As expec ted, these additional variables and serum insulin concentrations were highly interrelated. In a stepwise regression model, the serum insulin level was identified as the single best predictor of Lp(a) levels. Ne arly 25% of the heterogeneity in serum concentrations of Lp(a) could b e predicted by serum levels of insulin and testosterone, BMI, and the amount of strenuous exercise. CONCLUSIONS- The results of these studie s have shown that serum concentrations of insulin and testosterone, BM I, and strenuous exercise appear to account for the majority of predic ted nongeneric variability in serum levels of Lp(a). These observation s suggest the possibility in this group of healthy men that serum conc entrations of Lp(a) may be modulated by a complex interplay between in sulin action, obesity, androgen levels, and strenuous exercise.