HYPERLEPTINAEMIA - THE MISSING LINK IN THE METABOLIC SYNDROME

Leptin's association with fasting insulin raises the possibility that hyperleptinaemia is an additional component of the Metabolic Syndrome, or perhaps underlies the syndrome, This population-based study of Wes tern Samoans examined the relationship of serum leptin with insulin se nsitivity assessed by Homeostatic Model Assessment (HOMA) and componen ts of the Metabolic Syndrome. Two hundred and forty subjects (114 men, 126 women), aged 28-74 years, were drawn from a study conducted in 19 91. An oral glucose tolerance test indicated that 59 subjects had diab etes. Diabetic men had higher leptin levels than non-diabetic (6.0 vs 3.2 ng ml(-1)) but this difference was no longer significant after adj ustment for BMI. Leptin levels in diabetic women (24.7 ng ml(-1)) and non-diabetic women (22.6 ng ml(-1)) were not different. Leptin was str ongly, positively correlated with BMI, fasting insulin acid mean blood pressure after adjusting for age and sex (r > 0.43, p < 0.001), irres pective of glucose tolerance status, Linear regression models indicate d that leptin was associated with insulin sensitivity independent of a ge, BMI, waist/hip ratio, triglycerides, HDL-cholesterol, and hyperten sion. Similar models were computed with mean blood pressure or triglyc erides as the dependent variable, and including insulin sensitivity wi th the independent variables. Leptin was independently associated with mean blood pressure in men, but was not independently associated with triglycerides. Mean levels of 2-h insulin, triglycerides, LDL-cholest erol, and systolic blood pressure varied across tertiles of leptin in men after adjusting for age, BMI, and insulin sensitivity, and mean le vels in the top tertile tended to be higher than in the lowest tertile . These results indicate an independent relationship between leptin an d insulin sensitivity, but the equivocal results concerning associatio ns of leptin with components of tile Metabolic Syndrome make it unlike ly that leptin affects these directly.