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


METHODS
Cross sectional study, leptin concentration being measured in a subgroup of a population based sample.


METHODS
240 Polynesian men and women aged 28-74 years were selected to cover the full range of age, body mass index, and glucose tolerance.


METHODS
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/l, P < 0.001). Leptin concentration also correlated with fasting insulin concentration (r = 0.63 in men, 0.64 in women) and insulin concentration 2 hours after a glucose load (r = 0.58 in men, 0.52 in women). These associations remained significant after controlling for body mass index; effects of physical activity and of rural or urban living on leptin concentration were eliminated after adjusting for obesity, except values remained high in urban men. 78% of variance in leptin was explained by a model including fasting insulin concentration, sex, body mass index, and a body mass index by sex interaction term. Similar results were obtained if waist circumference replaced body mass index.


CONCLUSIONS
The strong relation of leptin with obesity is consistent with leptin production being proportional of mass to adipose tissue. The relation with insulin independent of body mass index suggests a possible role for leptin in insulin resistance or hyperinsulinaemia.
International Diabetes Institute, Victoria, Australia.
P
P
Zimmet
A
A
Hodge
M
M
Nicolson
M
M
Staten
M
M
de Courten
J
J
Moore
A
A
Morawiecki
J
J
Lubina
G
G
Collier
G
G
Alberti
G
G
Dowse
D000328:Adult; D000367:Age Factors; D000368:Aged; D001786:Blood Glucose / Q000378:metabolism; D015992:Body Mass Index; D003430:Cross-Sectional Studies; D048909:Diabetes Complications; D003920:Diabetes Mellitus / Q000378:metabolism; D005260:Female; D006801:Humans; D014905:Independent State of Samoa / Q000453:epidemiology; D007328:Insulin / Q000378:metabolism; D020738:Leptin; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000150:complications / Q000453:epidemiology / Q000378:metabolism*; D011506:Proteins / Q000378:metabolism*; D012423:Rural Health; D012737:Sex Factors; D014504:Urban Health
D001786:Blood Glucose; D007328:Insulin; D020738:Leptin; D011506:Proteins