High plasma leptin concentrations in hypertensive men but not in hypertensive women

Objective Previous studies on humans have reported higher leptin levels in women than in men, independent of body fat, and leptin has been correlated with insulin resistance in men but not in women, Since insulin resistance i s thought to play a role in raising blood pressure, we investigated sex dif ferences in leptin concentrations between hypertensive and normotensive ind ividuals, Methods Ninety-two nondiabetic hypertensive patients (48 men and 44 women) and 92 age, body mass index (BMI)matched normotensive control individuals w ere studied. Fasting plasma glucose, insulin, leptin and lipoprotein concen trations, glucose and insulin responses to 75 g oral glucose tolerance test (OGTT) and insulin suppression tests were determined, Results Fasting plasma leptin concentrations were higher in hypertensive me n than in normotensive men(5.1 +/- 0.5 versus 3.9 +/- 0.4 ng/ml, P = 0.015) , However, fasting plasma leptin concentrations were not significantly diff erent between hypertensive and normotensive women (11.8 +/- 1.0 versus 10.9 +/- 1.0 ng/ml, P = 0.440). Fasting plasma leptin concentrations showed goo d correlation with BMI, body fat, fasting plasma insulin concentrations, an d insulin area to OGTT in both men and women tall P< 0.001). However, fasti ng plasma leptin concentrations were related to steady-state plasma glucose (SSPG) concentrations, a measure of insulin sensitivity by insulin suppres sion test, in men only (P < 0.001). After adjustment for body fat amount, a ge and duration of hypertension, fasting plasma leptin levels still correla ted significantly with SSPG concentrations in men. These four variables tog ether accounted for a 67.9% variation in fasting plasma leptin levels in me n. In women, body fat amount was the only significant determinant for plasm a leptin levels. These four variables accounted for a 78.2% variation in pl asma leptin levels in women. Conclusions Our study confirmed a sex difference in leptin levels both in h ypertensive and normotensive subjects. Higher plasma leptin concentrations in hypertensive men but not in hypertensive women when compared with normot ensive control individuals was also demonstrated. These observations are co nsistent with the findings that plasma leptin is correlated with insulin se nsitivity in men but not in women. Further studies are needed to understand the causes and consequences of sex effects on leptin in blood pressure reg ulation. I Hypertens 1999, 17:1289-1295 (C) Lippincott Williams & Wilkins.