Serum leptin concentration, obesity, and insulin resistance in Western Samoans: cross sectional study

Abstract

Objective: To measure serum leptin concentrations in the Polynesian population of Western Samoa and to examine epidemiological associations of leptin with anthropometric, demographic, behavioural, and metabolic factors in this population with a high prevalence of obesity and non-insulin dependent diabetes mellitus. Design: Cross sectional study, leptin concentration being measured in a subgroup of a population based sample. Subjects: 240 Polynesian men and women aged 28–74 years were selected to cover the full range of age, body mass index, and glucose tolerance. Main outcome measurements: Serum leptin, insulin, and glucose concentrations; anthropometric measures; physical activity; and area of residence. Results: Leptin concentrations were correlated with body mass index (r = 0.80 in men, 0.79 in women) and waist circumference (r = 0.82 in men, 0.78 in women) but less so with waist to hip ratio. At any body mass index, leptin concentration was higher in women than men (geometric mean adjusted for body mass index 15.3 v 3.6 pg/1, PConclusions: The strong relation of leptin with obesity is consistent with leptin production being proportional to mass of adipose tissue. The relation with insulin independent of body mass index suggests a possible role for leptin in insulin resistance or hyperinsulinaemia. They were also strongly correlated with serum insulin concentrations even after adjusting for obesity in both sexes Concentrations were higher in women than men, even at the same body mass index or waist circumference Resistance to the effects of leptin may be important in human obesity Leptin may simply reflect the size of adipose tissue stores, but the independent association with insulin concentration suggests a possible role in insulin resistance or hyperinsulinaemia