Differential effects of obesity with and without hyperinsulinemia on plasma lipoprotein(a) concentrations in men

To determine the association of in vivo concentrations of insulin, obesity, and gender with lipoprotein(a) [Lp(a)] levels, we used a cross-sectional population-based survey of a multistage random sample of the Mexico City adult population. We studied 423 normoglycemic, normotensive subjects from an original sample of 825, comprised of 239 men and 189 women with a mean age of 38.6 years (range, 17 to 90). All subjects were divided into 8 groups according to body mass index, fasting insulin, and gender. Lp(a) concentrations (mg/dL) were similar in obese women with and without high insulin levels (19.9 v 18.6), but hyperinsulinemic obese men had significantly lower Lp(a) levels than normoinsulinemic obese men (7.9 v 29.4). In addition, the proportion of obese men with Lp(a) concentrations of > or = 30 mg/dL was significantly higher in the normoinsulinemic than in the hyperinsulinemic (29.2% v 0.0%). The frequency distribution of Lp(a) levels was shifted to a lower range in hyperinsulinemic men compared with normoinsulinemic men. Our results show that in men, hyperinsulinemic obesity is associated with low Lp(a) levels, while obesity with normoinsulinemia is related to increased Lp(a) concentration. These observations were not found in women. These findings may explain the conflicting results reported by several studies.